Duplicate invoice notice
The Duplicate Invoice notice means Mod AI detected that this invoice may be a duplicate of another one already in the system. Catching duplicates before payment is one of the highest-value things validation does.
What triggers it
The system fires the duplicate invoice rule when an incoming invoice shares both:
- The same invoice number.
- The same primary vendor.
When both match an existing invoice in the entity, the notice appears.
The default severity is error, which blocks the invoice until the notice is resolved. An admin can override this. See Configuring rule severity.
Resolve the notice
When the rule fires, a Document notices panel appears in the left column of the invoice detail page (between the page header and the document viewer). The panel header reads N Exceptions (where N is the number of active notices). Click the panel header to expand it; each notice appears as its own row with a short label such as Duplicate invoice and a small chevron to expand details.
The Document notices panel is the small bordered box on the left side under the breadcrumb. Click its header to expand and see each individual notice with its own row and action buttons.
- Click the Duplicate invoice row inside the expanded Document notices panel. The row expands to show the suspected duplicate's invoice number and a View duplicate link.
- Click View duplicate. The suspected duplicate opens in a side panel (or a new tab depending on the platform build) so you can compare both invoices.
- Compare them field by field: vendor, invoice number, invoice date, total amount, currency, and line items.
- Decide whether it is a real duplicate or a false positive and take one of the actions below.
If it really is a duplicate
Open the duplicate copy (not the original) and click the Void action in the invoice header top-right. The original stays in the system and continues processing. The Duplicate invoice row in the Document notices panel on the original clears automatically once the duplicate copy is voided.
If it is a false positive
If the two invoices are legitimately separate (same vendor and similar number, but different orders or billing periods), click the Mark as not duplicate button inside the expanded Duplicate invoice row in the Document notices panel. A small confirmation toast appears in the bottom-right of the screen. The system records your decision in the invoice's Activity tab so the same pair does not surface again.
Earlier versions of this article described a yellow "Possible duplicate" strip at the top of the invoice page. The current platform renders notices in a Document notices panel on the left side of the page (between the breadcrumb and the document viewer) rather than as a top-of-page strip. The functional steps (click the notice, view the duplicate, decide, mark or void) are the same; only the location and presentation differ.
Always review both invoices before dismissing a duplicate notice. Paying the same invoice twice is a costly AP error.
How the system tracks decisions
When you mark a pair as "not duplicate", the system stores that decision and does not re-fire the same notice on the same pair. New invoices from the same vendor with different numbers still get checked normally.
After resolution
Once resolved (either by voiding the duplicate or dismissing the notice), the invoice continues into approval routing. If you click Validate the rule runs again and confirms the resolution.