Solution : https://service.sap.com/sap/support/notes/320459 (SAP Service marketplace login required)
Key words : 
additional key words co40, production unit, planned order, production order, header quantity, requirements quantities, longer correct, requirements quantity, numeric inaccuracies, implement notes 153683
Related Notes : 
       
| 540614 | Partial conversn: Wrong component qntities in collctve order | 
| 174538 | CO40: Incorrect order quantities in collective order | 
| 153683 | Part.conv.plnd ord.: qty of dep.orders in col.order |