Rated 3 out of 5 stars
Ok, this addon pretty old and not updated to the new TB UI,
BUT it DOES work while searching for duplicates and find almost all dupes.
the new alternate version (developed by somebody else) has quite a nicer and updated gui, but lacks in finding the simplest dupes (just 50%).
so this version is needed too, if you want to find 95% of your dupes.