Duplicate Invoice Numbers

In 11i the functionality for duplicate invoices looked at the supplier level. In R12 the functionality changed to look at the site level. My understanding is patch 9105666 would change the R12 functionality to look at the supplier level (like 11i) for duplicate invoice numbers. Is this correct?

I'm asking because we applied the RPC (Core) with patch 9105666 and there is no change in functionality. The only time we receive a duplicate invoice number message is when we use the same site for the supplier. We have any suppliers with multiple sites.

Thanks,

Kim Scott