R470412 check for duplicate invoice numbers?

We had a situation where we received an EDI (810) and paper copy of the same invoice.  We processed the paper invoice first through standard voucher entry.  Then a few weeks later we processed the EDI invoice and the R470412 program created the voucher even though it was a duplicate invoice number.  We have our AP constants set to a hard error on duplicate invoice number edit.  Shouldn't R470412 check for duplicate invoice numbers?