Receipt Reversals when Inventory is not available on hand

We operate in a distribution enviornment where we buy and sell products. Frequently we land into situations where we have received material and them immediately shipped material out. Later at the time of voucher match we notice discrepancies in PO and we are required to reverse the receipt. But with no on-hand inventory we are unable to reverse the receipt. So we add another line to the original PO. Receive it. Then unreceive the original line. Make corrections. Receive the original line. Then we unreceive the secod line and then cancel the second line. While this is Ok, from a