How can we restrict same invoice number across multiple Operating Units in EBS R12

Summary

We had come across an issue where the invoice was entered in 2 different OUs with the same details and got paid with 2 different payment methods.

Content

We had come across an issue where the invoice was entered in 2 different OUs with the same details and got paid with 2 different payment methods. How can we control the same invoice isn’t paid by two entities.

Do we have any control on invoice status so that the members of the team would know whether an invoice has been processed?  Since the emails go to an email address for the team, how do the team members know who is processing which invoice?