"Bookmark Dupes" does it's job __very well__, and the expert options are a very good addition.

May be the user interface could be improved.

But this nice plugin already saved me countless hours of work, removing thousands(!) of duplicates from a crufty, ancient collection of bookmarks, merged from several computers' FF installations, so ⭐⭐⭐⭐⭐ from me!

Thanks for the good work! Keep it up!