Invoice-led
Duplicate Invoice Detector
Paste invoice rows and flag exact or likely duplicate merchant invoices before they get paid twice.
Duplicate check
2 warnings found.
Checked 3 rows for repeated references and same supplier/date/amount matches.
Exact supplier and invoice reference repeat: MKM|INV-1042.
Likely duplicate by supplier, date and amount: MKM|2026-05-12|428.40.
What it is for
Built for real merchant paperwork, not generic accounting.
Built for the end-of-month pile where the same merchant invoice may have arrived by email, statement and paper copy.
Looks for repeated invoice references by supplier.
Flags same supplier, date and amount even when the reference is different.
Keeps the next step practical: check, hold, or send the paperwork in.
Guidance note
Duplicate invoice matching rules
Reviewed by ConstructionIntel on 14 June 2026.
Duplicate invoice checking starts with exact matches, then moves to likely matches. An exact duplicate usually has the same supplier, invoice reference and amount. A likely duplicate may have the same supplier, date and amount but a different or missing reference, so it should be held for review rather than paid twice or treated as fraud.
Group rows by supplier before comparing invoice references.
Flag exact repeats where supplier, invoice reference and amount match.
Flag likely repeats where supplier, date and amount match but the reference differs or is missing.
Check the supplier statement and payment run before deciding whether to hold, query or file the row.
What happens next
If it looks odd, send the invoice.
You get exact duplicate warnings and likely-match warnings you can check before paying or forwarding to your accountant.
Send the invoice