Sort By Similarity Seemingly Irrelevant To Image Duplicates

[Darius1968]

So, I just did a duplicate search on 69 image files, and it turned out to be 100% accurate.  Where I ran into a slight problem is when I pinned all 138 images (69 originals + 69 duplicate results), and then, tried to sort them by similarity, where everything was all out of order.  Why is this?