[EVa5I7bHFq9mnYK]

I doubt sha1 hashes are used for this. Those image hashes should match files regardless of orientation, cropping, resizing, re-compression, color correction etc. The collision could be far more frequent with these hashes.

[bluGill]

The hash should ideally match even if you use photoshop to cut the one person out of the picture and put that person into a different photo. I'm not sure if that is possible, but that is what we want.