AUTO PAYMENT - 2 Proposals for one vendor.

Dear gurus,

I can not making auto payment for one vendor code at the same time in 2 different log in accounts.It means I can not run 2 proposals (free selection for 2 different document types) at the same time for one vendor.

EX: I have some activities, one accountant is responsible for one activity. Because one document type is used for a relevant activities, so I need to run at the same time at least 2 proposals (for 2 accountants in 2 different places) for one vendor code.

Would you please tell me if I can make this and how to make it work?

Thank you very much.