Thanks Richard for your reply.
I use GP 10, and I received the full amount of the PO and this affects the item stock as well, so as a concept system should not allow me to receive the full quantity twice against the same PO, because this will duplicate the quantity in the store.
Second point I want to mention is that even if i did the return for this receiving system still allows me to enter match invoice this received quantity even after returning it and it doesn't consider that these quantities have been returned.
Please advice if i'm mistaken.
Thanks