Hi Hari,
Please how error handling configured in DTP.
Not only duplicate records may be some other issue like special char, lower case letters , goto error stack and click on record it will show exact error message.
Then edit and execute Error DTP.
Some time, let say if any error material number 12345 , this will go update in error stack , while updating again if 12345 come, since 12345 already in error stack hence it will go and update error stack again.
Please check ,
RSB_ANALYZE_ERRORLOG to identify DTP wise how many error stack records available
RSBM_ERRORLOG_DELETE to delete error stack.
Thank you,
Nanda