Multiple unnecessary folders appear in Outlook folder tree
In your mailbox, you see many folders named the file so that changes to the file will be reflected in your item, and these files cannot be removed (Fig. 1.).
If you started seeing multiple redundant folders in your Outlook folder tree, this is most likely caused by one of your Outlook add-ins.
The solution to this problem is to disable all your Outlook add-ins, restart Outlook, and delete the unnecessary folders.
Note that this kind of behavior is typically related to antivirus software, so you may want to start disabling add-ins from the ones associated with such programs.
Then, start turning on your add-ins one by one until the problem comes back. At this point you will know which add-in causes the issue.