Occasionally users have ask me if Bookends can find and remove duplicate attachments that have different names. Bookends can't do that. But a user has reported that dupeGuru can do this nicely.
https://dupeguru.voltaicideas.net
Note that if you use a utility like this any reference it is attached to will no longer be able to find it. You can remove this "orphaned" attachments in Bookends and/or reattach the version of the (usually PDF) that you kept.
Jon
Sonny Software