Duplicate invoice: why ERPs reject it

Many ERP systems automatically reject an invoice when it appears to be a duplicate of an earlier submission. This is a structural control designed to prevent double payment and accounting inconsistencies.

Typical trigger: the same vendor + invoice number combination already exists in the system, or the same document gets submitted more than once.

What a duplicate invoice means in ERP systems

Common reasons duplicates happen

Vendor resubmits after not receiving confirmation
AP team uploads the same invoice twice by mistake
Invoice number reused (credit notes or revised invoices)
Multiple channels (email + portal + EDI) submit the same document
Minor PDF changes, same invoice number (ERP still flags it)

How to prevent duplicate rejections

Enforce unique invoice numbers per vendor
Track submissions and confirmations internally
Use a consistent naming rule for revised invoices (e.g., INV-123A)
Validate before ERP submission to catch duplicates early

Validate an invoice (preview)

See the 30 checks

Related: Invoice total mismatch

Structural validation only. No fiscal, legal, or accounting checks performed. Files are processed temporarily and are not stored.