Extra shipment line on PO

We have a PO create with 3 lines on the second line they originally had a quantity of 55, they needed to adjust the quantity to 17 because the balance was paid on another PO.

They marked 17 as the Quantity received and 38 as the Quantity cancelled in the shipments screen however a new shipment line was created with another 17 of quantity due, these two lines both now require reapproval but the second line should never have been there.

Not sure what was done to get the second line but it's causing issues when we try to correct it, is there a way to reverse a shipment line.