We received a Make From item on a PO and it properly relieved the inventory of the part that is in the BOM of the M type.  The price was very wrong though and to fix it I did a negative receipt of a fully received line.  This put the component back into inventory.  Then changed the price on the M type and re-received the line, and the component stayed in inventory, and the cost of the make from was off by the cost of the component.  
Should I have known better than to try to receive a M type line twice(or three times if you count the un-receive)?  Un-receiving it again and putting it on a new line worked.