In the File or Site Migration Global Settings, you can choose whether a file at the target should be kept if a file at the source has an identical name.

During a File or Site migration, your files already exist in the target prior to the migration. They were either migrated manually or with another tool.
In this case, the files that already exist in the target will not be pushed during the first pass because Sharepoint will not accept them. They will be refused from Sharepoint with the error “File with the same name already exists.”

You have three options in this scenario.

1. When you choose the option “Ignore”:
   This option will simply ignore these files as they are already in the target. The files will be marked as Ignored with the message “File with the same name already exists”.
2. When you choose the option “Overwrite”:
   1. During the first pass, the files that already exist in the target will all be marked in error from Sharepoint saying “File with the same name already exists”.
   2. To overwrite these files, you need to rerun the migration. The migration tool will then push the files and will overwrite the files in the target. CAUTION: The migration needs to be run twice to be able to overwrite the files in the target.
3. When you choose the option “Copy”:
   1. During the first pass, the files that already exist in the target will all be marked in error from Sharepoint saying “File with the same name already exists”.
   2. To push a copy of these files without overwriting the existing target files, you need to rerun the migration. The migration tool will then push the files appended with the word _old and will not overwrite the original target files. CAUTION: The migration needs to be run twice to be able to overwrite the files in the target.