Solution : https://service.sap.com/sap/support/notes/306973 (SAP Service marketplace login required)
Key words : 
additional key words co11, program errorfirst implement, attached program correction, goods issue postings, incorrect goods movement, main operation confirmations, goods movement, control key, -operation confirmations, main operation
Related Notes : 
       
| 386310 | Multiple GR by-product despite firm quantity | 
| 177799 | Incor. qty of goods receivd for fixed by-product |