Cynically, I'm going to say you either find unsurprising matches (eg. photos of the same group of people taken on different days) or even more convincing and ha

Cynically, I'm going to say you either find unsurprising matches (eg. photos of the same group of people taken on different days) or even more convincing and hard-to-detect false positives. If your goal is explicitly to find something extremely rare - unexpected face matches in different places - you will be flooded with false positives even if the false positive rate is fairly low.