Occasionally our customer service deals with items coming back to the company that were incorrectly picked by our fulfillment department & shipped to the customer. To make inventory accurate currently we issue an RMA for the item that should have been sent (to give the customer a reference number), then close it once the item they received in error is sent back (b/c we do not want to return it, just actually ship out the right thing!).
In the next step we are using a rather roundabout process that involves non-inventory items placed on the solution sales order with a description telling our fulfillment department what to send  (thereby not taking an additional item out of inventory that was supposed to be sent correctly the first time).