Most systems catch the duplicate that looks identical. The expensive ones look slightly different.
Built-in accounting or ERP checks usually catch only exact repeats of supplier and invoice number. AP automation adds wider matching before payment, Excel-based tests catch near-matches cheaply if run before every payment run, and recovery audits find what got through, usually for a share of what they recover. Most businesses need a preventive test before payment plus a periodic look back.
| Option | What it catches | What it misses | Cost |
|---|---|---|---|
| Built-in ERP or accounting software check | Exact repeats of supplier and invoice number | Reformatted numbers, duplicate supplier records, manual payments | Included |
| AP automation platform | Exact and some fuzzy matches at invoice capture | Payments made outside the platform; depends on configuration | Subscription, often per invoice or per user |
| Excel-based duplicate tests | Reformatted numbers, same amount and date, near-dates, duplicate suppliers | Anything if not run before every payment run | Low, one-time |
| Recovery audit | Duplicates already paid, often years back | Nothing in the future: it finds losses after they happen | Usually a percentage of amounts recovered |
If you already have an ERP, keep its check switched on, but do not rely on it alone. If invoice volumes are high and your team is stretched, AP automation can pay for itself through time saved, not only duplicates caught. If volumes are moderate, a structured Excel test before each run gives most of the protection for a fraction of the cost. A recovery audit is worth considering once for older years, then rarely if your preventive tests work.
The options are the same in the UK and the US. In both, recovering a duplicate is usually straightforward if you ask promptly with evidence, but much harder after a supplier has closed its books for the year, so speed matters.
Paste your invoice list and see likely duplicates in minutes. Free Excel file: enter your work email to download it.
The Accounts Payable Control System runs four duplicate-invoice tests, supplier master fraud checks and a three-way match on every invoice, with a payment run release gate that blocks release while exceptions are open. Excel, no macros, one-time price.
Most systems compare supplier and invoice number exactly. If the number is typed differently or the invoice is entered against a second supplier record, it does not look like a duplicate to the system.
They can be, especially the first time, because they review years of payments. Because they are paid from what they recover, the cost only arises if they find money. Prevention is still cheaper than recovery.
Before every payment run, on the invoices about to be paid, plus a wider look back at least once a year.
Contact the supplier with both invoice references and payment dates, and ask for a refund or a credit against the next invoice. Record the recovery, then fix the cause, such as a duplicate supplier record, so it cannot happen again.
Last updated 18 October 2026. General guidance for finance teams; check it against your own policies, systems and local rules.