Solution : https://service.sap.com/sap/support/notes/816343 (SAP Service marketplace login required)
Key words : 
mysap discrete industry solution mysap aerospace & defense mysap engineering & construction mysap hitech mysap automotive solution, system encounters performance problem, external material number reason, industry add-ons, terms interchangeable part, code corrections attached, industry sector, internal material number, mpn conversion exit, conversion exit
Related Notes : 
       
| 769906 | Material number same as existing MPN is allowed for creation |