How to check for duplicate supplier payments
A duplicate invoice is not necessarily a duplicate payment. A ledger can repeat a row, a supplier can reuse a reference, or a payment can be split into installments. Start with records that let you distinguish these cases.
Export the evidence you need
Include supplier, invoice reference, amount and currency. Add payment status and a unique payment reference when available. Keep one row per transaction. Include the original invoice year in the reference when your accounting system reuses numbers.
Match references before matching amounts
Two invoices for $100 may be legitimate monthly bills. Billquiet groups normalized supplier and invoice references within the same currency. If the amounts are identical, all rows are marked paid and payment IDs differ, it raises a possible duplicate-payment finding.
Verify against the source
Compare the flagged records with the actual invoices and bank statement. Confirm the payment IDs are distinct bank transactions and not internal ledger references or installment allocations. Ask the supplier how the payments were applied before requesting money back.
A worked example
Illustrative records: invoice NH-1024 for $840 appears against PAY-001 and PAY-009. That produces $840 of candidate exposure, not $1,680 of savings. If both rows use PAY-001, the candidate exposure is zero because the export may simply repeat one payment.
Billquiet has a built-in sample showing this distinction alongside an amount mismatch and a credit to reconcile.
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