Dummy serial number profile

Hi experts,

I have questions. There are incoming Idocs to SAP which creates IBD in the system. Now at the suppliers end it is mandatory to pass serial number in the Idoc. It is passed through SERNR field. For bypassing this, I created one dummy serial number profile(ZDUMMY) and maintained in material master. Now, the Idocs which are sent from suppliers side have multiple E1EDL11(serial number field with same value. Now the questions:

1. Is maintaining ZDUMMY in material master will have same results when we leave the serial number profile in material BLANK.

2. The Idocs are failing . they have duplicare SERNR. Is this the reason for failing.

thanks..