Refund Invoice Numbers

When you run the AR Refund process the resulting output into the staging tables uses the field ITEM as the INVOICE_ID.  If the ITEM has multiple lines that were selected in the Maintenance Worksheet then there are duplicate Invoice ID's that get created when the voucher build process is ran.  This results in errors and manual correction by the AP group is needed.  Is there a way that we can tell the system to create the INVOICE_ID based on a combination of the ITEM and the LINE_ITEM so that the duplication errors are not created and manual correction will no