Field notes
Duplicate invoices: quiet patterns that inflate payables
Exact duplicates are rare once a system blocks identical invoice numbers. Near-duplicates are common: same vendor, same amount, invoice number with a trailing letter, or a credit note rekeyed as a fresh bill.
Split approvals make the pattern worse. Two department heads each approve half of a service fee that should have been one invoice under a higher threshold.
An afternoon review technique: sort the AP listing by vendor and amount, then scan for clusters within a few days of each other. Pull those packets first. You will not catch everything, but you will catch the expensive habits.
Vendor master hygiene helps. Two registrations for one supplier — one under a trade name, one under a legal name — invite double entry. A vendor integrity pass pairs well with any approval review.
When a duplicate is confirmed, document whether cash already left. Remediation for paid duplicates is a recovery conversation; remediation for unpaid duplicates is a block in the next payment run.