File was migrated with _Duplicate appended to file name because file with same name but different unique ID already exists on the target. We are encountering this across multiple Sharepoint sites on thousands of files. Is there something we can do to avoid this happening in the future? What could have potentially caused this to happen?
The source SPO file was reuploaded with the new uniqueID
The issue will only happen when source SPO file was deleted and the new one will be uploaded instead. This will cause the source file to receive a new SPO uniqueID.
ODMSP is checking file's uniqueID in order to detect which target file is the same as the source. For example, file can be renamed and this can affect migration. Thus, ODMSP never relies on filenames.
So if ODMSP sees the file with the same name, but different uniqueID, then migration will create a new file with the "_Duplicate" suffix.
It's up to the end client how they want to deal with this situation. They can keep both versions of the file. Or they can delete the original one in the target SPO (old uniqueID), then rename the _Duplicate filename to one without the suffix in order to continue to be able to remigrate delta changes.
Please note, that if end client will delete the target _Duplicate file, then re-migration will create it again, unless the target original filename will also be deleted as well, prior to remigration.
