How to Identify a Duplicate Invoice

It doesn’t look right. Logo? Check. Correct goods? Check. But, it feels off. Duplicate invoice fraud can strike any business. A huge problem that escalates as the volume of invoices your business processes increases. Premeditated or a genuine mistake, duplicated invoices will impact. Financially. Alongside a loss of trust and reputational damage.

Let us show you how we can help you with duplicate invoice detection.

Fraud by duplicate invoices is a prolific crime in which money is diverted from the correct recipient to a fraudulent one. Hard to police when your team have to verify hundreds if not thousands of financial documents every day. 

I’m going to explain what duplicated invoices are and how they occur. How they’ll hurt your business. How to prevent them. 

Let’s go…

What is a duplicate invoice?

A duplicate invoice, or double invoice, refers to multiple copies of the same invoice issued for the same transaction. 

It could be a genuine human error. It could be invoice fraud. Either way, if processed it’ll clog up your admin communication and hit your business with unplanned costs.

They take various forms. An identical invoice submitted multiple times. A manipulated invoice. A duplicate invoice submitted via different channels.

If missed or ignored, your AP team will process. Unaware that double payments are being made.

If you’re still following a manual document processing strategy, identifying these invoice copies will be time consuming and inefficient. Manually matching vendor, invoice number, date, and total is a slow process. Plenty of discrepancies will be missed.

A post that might be worth a quick read – The best invoice automation software on the market.

How does a duplicate invoice happen?

Accidentally. Intentionally.

Invoice copies are a result of human error, overly complicated internal business processes, and fraud. Double invoices occur because of…

  • Manual data entry errors
  • Incorrect pricing
  • Mistakes in a master vendor file
  • The same invoice sent via multiple channels
  • Altered quantity or price
  • Canceling a vendor invoice after payment
  • Large volume of vendor invoices
  • Inadequate data validation

Do you have full visibility of the entire invoice processing workflow? I realize that if you’re processing manually, it’s a massive ask. A lack of oversight or sketchy controls means inadequate checks. Duplicate invoices will easily slip the net.

If you’re looking to move away from manual document processing, take a look at our guide to invoice processing automation.

How do you accidentally create a duplicate invoice?

You can’t always blame an identical invoice on some dodgy character. Innocent mistakes happen. Manual data entry often leads to fat finger episodes. A breakdown in communication between teams. Invoices submitted via multiple channels. Invoice reconciliation. Approval. A vendor sending a follow-up invoice because of late payment

With some vendors using an automation feature in their ERP system to send an invoice daily, if payment hasn’t been received. 

That’s a lot of duplicates!

For example, nowadays, invoices are emailed on the whole. But, some companies still send paper copies too. 


A duplicated invoice.

If you’re working with large volumes of invoices, tracking is problematic. Especially if you’re doing it manually.  

How does a fraudster create a duplicate invoice?

You can’t hide under a rock. 

There are people out to defraud your business. To steal. Issuing identical invoices with small changes intended to hoodwink your accounts payable department. Financial fraud can stem from dishonest vendors or employees.

  • Vendor fraud – a vendor knowingly submits the same invoice multiple times, with minor changes such as a change of date or invoice number.
  • Internal fraud – an employee takes a legitimate vendor invoice and rather than paying into the vendor’s bank account, they redirect to a third-party’s account. 

“31% of fraud cases are perpetrated by an employee, and 26% from collusion between internal and external actors.” PWC’s Global Economic Crime and Fraud Survey 2022

This would be a good read, to learn about other instances of invoice fraud – How to identify fake invoices.

How do duplicate invoices impact my business?

Double invoices are the stuff of nightmares. As if financial loss isn’t enough, you’ll also end up working with unreliable financial statements and chaotic cash flow. Reconciliations will take an age, your vendor relationships will be put in jeopardy, and your business’ reputation could damaged.

Understand the havoc artificial invoices can reap and the urgent need for a solution to protect and prevent…

Financial loss

Duplicated invoices can lead to overpayment. Your business will lose money. This will harming your bottom line and profitability.

Accounting errors

Manipulated invoices will mess up your financial records and accounting systems. Inevitably, your financial reports won’t add up. Monitoring expenses and revenue will be a nightmare.

Cash flow problems 

A duplicate invoice will mess with your cash flow management. Money lost on paying the same invoices twice will mean your organization won’t be able to meet financial obligations.

Compliance and auditing

If your financial records are peppered with inaccuracies, audits will be a painful process. Auditors digging deeper, leading to fines or penalties, is a real possibility.

Vendor relationship breakdown

If payments are late or wrong, expect to feel the wrath of vendors. A breakdown in vendor relationships will bring frustrations down the line as trust and satisfaction take a hit.

If you’re still using manual document processing and you’re concerned about invoice duplicates, it’s time to consider automating your AP workflows. If you’re already automating, but your strategy isn’t working, time to upgrade to AI document processing.

Take a look at the best accounts payable automation software.

How can my AP team protect our invoice processing workflow?

So, we’ve already established that false invoices will damage your business operations and increase the workload of your AP team.

Let’s look at two key ways to secure your invoice processing workflow…

Classifying invoices

Invoice classification assigns labels to invoices based on their content. Vendor, customer, amount, date, payment status, etc. In invoice processing, it helps you to sort, match, and verify invoices.

Does your process allow you to see which invoices have been paid? Which ones need to be double checked. Which are late?


You’re on the way to creating a duplicate invoice. Zero classification means zero visibility. You don’t know what’s going on. That’s when things go wrong.

How to solve lack of visibility?

  • AP automation – increase the accuracy, efficiency, and security of your invoice verification process
  • 2-way/3-way matching – match invoice data with purchase orders, goods receipt notes, and contracts
  • Confirm line item data – match goods, quantity, price with the vendor invoice
  • Business rules – automatically compare vendor invoices with past transactions

Verifying vendor details

Your AP team creates a master file for each vendor. Sounds like it should be simple but things can get tricky if vendors have multiple branches issuing invoices. There’s a danger of your AP team having more than one master file for a single vendor. 

See where I’m going with this?

To avoid the creation of double invoices your accounts payable team should…

  • Verify vendor information – use business rules to confirm vendor number, invoice number, and invoice amount.
  • Match the vendor master data with the vendor – postal code, vendor name, and invoice amount.
  • Implement advanced AI and automatically verify based on historical data which will flag discrepancies.
  • Invoice approval workflows capture and categorize vendor name, amount, etc., and then determine the level of approval needed.

Rossum’s automated approval workflows.

How should my AP team resolve duplicate invoices?

When your accounts payable team spot a potential duplicate invoice, the first step is to prove whether it’s authentic or not. Compare it with your existing records such as the relevant purchase order or paid invoices from the same vendor.

If it’s a copy, it’s time to speak with the vendor to ensure you avoid duplicate invoice payments. If a second payment has already been issued, your AP will need to issue a refund or credit note to the vendor. 

How to prevent duplicate invoices

Accounts payable automation software.

Yep. That simple. Features like automatic matching, real-time visibility of invoice status, approval workflows, duplicate alerts. Implement an intelligent document processing solution like Rossum, for unmatched accuracy and fraud detection.

Rossum Aurora - AI engine - brings a whole new level of accuracy compared with previous AI generation. Helping customer identify duplicate invoices.

Rossum Aurora is our advanced AI engine. It requires 10x fewer training examples to reach desired accuracy levels, compared to previous AI generation.


If you’re still working with processing invoices manually, you’re going to struggle to catch all those invoice duplicates. Matching supplier, invoice number, invoice data, amount sounds okay, might work for a few invoices. But, as the volume increases…

Using an AI document processing solution you can avoid duplicated invoices…

Single entry point

If you’re receiving invoices from multiple vendors in different locations, the likelihood of receiving duplicate invoices is increased. Leading to duplicate payments. Having a centralized point of entry will prevent duplicate invoices entering your process from different departments.

Up to date vendor master files

Keep your vendor master data clean. Updating new information and deleting anything out of date. Ensure there are no vendor duplicates, where a slight change to a name has created a copy. 

Automatic data matching

Purchase orders prove a transaction has taken place. Helping you see which goods have been ordered and delivered.

AP software will automatically match invoices with purchase orders. Flagging when there’s a mismatch.

Approval workflows

An automated invoice approval workflow ensures a review and payment authorizations identify discrepancies and stop any payments being made on duplicate invoices.

How does AI help to detect duplicate invoices?

An intelligent document processing solution like Rossum uses AI to do advanced checks. Identifying duplicate invoices by automatically comparing line items when a vendor issues multiple invoices on the same date or over a short period of time.

Rossum’s transactional document automation platform automatically capturing line items.

From data capture, validation, and three-way matching, to duplicate invoices and mismatched data, our IDP solution will red flag discrepancies immediately. 

“51% of surveyed organizations say they experienced fraud in the past two years, the highest level in our 20 years of research.” PwC’s Global Economic Crime and Fraud Survey 2022

You might want to take a look at how to fight back with Document Fraud Detection Software for more information.

As well as tracking for duplicate invoices, an AP automation solution will help your accounts payable team identify anomalies in spend and payments. Analyzing patterns means your team will be able to see spikes in vendor spend or the volume of invoices submitted.

If you’re short on time and don’t have space for an hour-long demo. Knock yourself out with our interactive demo. See how intuitive our AI-powered document processing platform is, and how we can revolutionize your business operations and drive efficient document workflows.

Alternatively, put our platform to the test with your own documents. How Rossum works is a post that explains how you can sign up for a free trial and see how we can automated your document processing end to end.

Duplicate invoice detected by Duplicate Handling extension. Red buttom bottom left.

Duplicate invoice detected.

Red alert box showing which invoice is a duplicate.

Reject duplicate.

Prevent duplicate invoices with Rossum

Duplicate invoices are going to cost your business. Whether it’s paying invoices twice or your team wasting time hunting and eliminating them.

Automating the accounts payable process end to end will eliminate the threat of duplicate invoices. 2-way/3-way matching, real-time tracking, and red flag alerts will protect your business against accidental and intentional invoice copies.

Rossum’s document automation solution will improve your invoice workflows. Your organization will…

  • Eliminate manual data entry
  • Increase accuracy with AI OCR software 
  • Reduce processing times
  • Protect against invoice fraud
  • Tailor your workflows to meet your business needs
  • Integrate with your ecosystem – SAP, Coupa, Workaday, and more

Ready to see how Rossum can be integrated into business operations? Book a demo!

Duplicate invoices FAQs

How does a duplicate invoice happen?

A duplicate invoice happens either accidentally or intentionally. A manual data entry error or an act of fraud. Both lead to a single invoice that’s been duplicated, being paid multiple times.

What problems can a duplicate invoice cause?

If a duplicate invoice goes undetected, your business can suffer a financial loss and problems with cash flow and profitability. Vendor relationships will also suffer because of potential late payments.

What do I do if I receive a duplicate invoice from a vendor?

If you discover a duplicate invoice, your AP must inform the vendor to confirm the error. If a duplicate payment has already been made, a credit note can be issued.

Will a duplicate invoice involve my legal team?

If the duplicate invoice was issued by a vendor with the intention of overcharging you, receiving payment for goods or services never received, or it was internal fraud committed by an employee, yes. The person/vendor responsible for the fraud would/could face legal action if found guilty.

Ready to hunt for duplicate invoices?

Don’t get caught out by dodgy fraudsters. Protect your finances with automated accounts payable workflows.