Duplicate images

I've been using Dup Detector to find duplicate image files (damn you 4chan). I've just found out that it doesn't detect .gif files though.
Are there any programs that work the same as Dup Detector, but can support gifs?

>>1
You're doing it wrong

1. Convert old, obnoxious, limited GIF format to PNG
2. Run DupDetector
3. PROFIT