So I have a problem. I have WAY too many hard drives and backups from decades of computing. I just hoard everything. The issue is now I don't know what I have duplicates of and what I don't. or when I want to format an old external drive for something else, I'm not sure if I actually have a backup of it.

I just want a way to basically compare folders and see what files are missing or what are duplicates. I'm fine with CLI but I may prefer a GUI for this so I'm not deleting files by accident as easily...

I have searched around for this question but all the solutions seem way too complex for me.