Error while loading unl, which contains SRC ITEM


I am getting errors while loading a unl that has changes of an SRC Item. Can someone help me out. I have to make manual changes in all environment, because of this error. The error is as follows.

Additional errors have been written to the log. Contact your system administrator (file.load,create.file.1)
SQL code=957 message=ORA-00957: duplicate column name (file.load,create.file.1)