Why exact matching misses real duplicates
Invoice numbers may contain spaces, prefixes, punctuation, OCR errors, or deliberate variations. Vendors can appear under different legal names, and recurring amounts can be legitimate. Detection therefore needs multiple signals rather than one equality check.
Signals worth combining
A risk score can combine normalized invoice number, vendor identity, amount, currency, date proximity, purchase-order references, line descriptions, bank details, and the history of prior payments.
- Exact and fuzzy invoice-number similarity
- Same vendor, amount, and close date
- Repeated PO or receiving evidence
- Near-identical line items
- Unexpected bank-detail changes
- Payment timing that differs from the vendor pattern
Show the reviewer the pair
A useful alert places the suspected invoices side by side, highlights matching and conflicting fields, links to source documents, and explains why the pair was flagged. The reviewer should be able to clear, hold, or escalate without reconstructing the evidence manually.