MR11 Query

Experts,

Have a query related to MR11.

This transaction is used to clear outstanding entries in the GR/IR account. Suppose if I do MR11 for a PO for which GR is already posted, it will clear the GR/IR entries and post account maintenance document. Now if I post the invoice for the same PO, it allows me.

My query is- if the GR/IR clearing is already done for the PO, why the system should allow invoice posting again?

Please advise.

Thanks,

Nilesh