please remember that some other extension could be using the FOF framework and (more importantly) they did not register themselves as dependencies inside FOF framework. This means that even if no extension officially "announced" that is using those files, maybe you have.
My suggestion is to simply ignore it, Akeeba Backup will automatically handle the updates for the FOF library.
However, if you do not use any software from Akeeba (and you feel brave), you can try to remove FOF 4.x library.
PLEASE NOTE: There's a chance that your site will break. If you have FOF installed it means that someone is using it. My suggestion would be to do such test locally and triple check everything, only then remove the library.
Developer and Support Staff
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