Hi iam trying to update payment term,payment priority and vendor type throuhg api's ap_vendors.updat

Hi iam trying to update payment term,payment priority and vendor type through api's ap_vendors.update row() and ap_vendor_sites.update row() in oracle apps 11i which they will provide in the flat file  with other columns vendor number,vendor name,vendor site code,new term,new payment priority and vendor type.I wrote package for this requirement and ran the concurrent program .When i ran for the first time it is updating then when i ran second time one record is showing error msg in the staging table as well as in the log file as ORA-20001: APP-SQLAP-10357: This Site name already exists for this supplier.   Re-enter