How to Prevent Supplier Overpayment When Prepayment and Standard Invoice Are Matched to the Same PO

Business Scenario:

We have a requirement to prevent supplier overpayments when both a prepayment invoice and a standard invoice are matched to the same Purchase Order (PO).

Example:

1. A Purchase Order is created for 1,000.
2. A prepayment invoice for 20% (200) is created, matched to the PO, and fully paid.
3. Subsequently, a standard invoice for 1,000 is received and matched to the same PO.
4. Oracle allows the standard invoice to be validated, approved, and paid for the full 1,000 without enforcing the application of the previously paid advance.
5. As a result, the supplier receives a total payment of 1,200 against a PO valued at 1,000.

Expected Behavior: