Back when I was more excercised about nuking dupes, I used DoubleKiller
. Last update was 2015, as the author is probably working on his PhD.
Two more different approaches:Cathy
is a media cataloguing tool; in my experience, it's very fast at making catalogues. It has a "search duplicates or singles" feature.
Nir Sofer's SearchMyFiles
has a "Find duplicates" feature that can be combined with normal file-finding criteria.