Duplicate Invoice Number for same supplier but different site

 Hello Folks,

We just upgraded to R12 from 11i and I found out that we are able to create invoices with the same invoice number for one supplier but with different site. Is this a standard functionality?

Also if it is, is there a way we can restrict that from happening? My thoughts are that we can do a personalization for manually entered invoices which would check to see if the invoice number being entered already exists or not for that supplier, no matter the site. Does that seem feasible?

For invoice imported from other sources, is there a way to check for this case of duplicate invoice number (again, no matter the site) for one supplier and then hold these invoices in OIT unless users manually process them?