100% match in Picture mode for Contents type returns very similar, but not equal pictures

[silvavlis]

I want to find duplicated pictures with different metadata (typically because I added some tags to one of the pictures). Therefore a typical filed duplicates finder doesn't fit for my use case.

The documentation says regarding the Picture mode of type Contents of dupeGuru

A threshold of 100 adds an additional constraint that pictures have to be exactly the same (it’s possible, due to averaging, that the tile comparison yields 0 for pictures that aren’t exactly the same, but since “100%” suggests “exactly the same”, we discard those ocurrences).
Therefore I was convinced that I had found the right tool for the job.

But to my disappointment the selection Picture mode + Contents type + 100% Filter Hardness is returning extremely similar (but slightly different) pictures. BTW, I suppose, that's what is being called "threshold" in the mentioned documentation.

How come that I have so similar pictures? Because I shoot them with the burst mode of the camera.

Can it be, that 100% means that the blockify versions of the pictures are exactly the same, but since the blockification process is reducing the information, the pictures are extremely similar, but not exactly the same?

[silvavlis]

I just found out, that no match of 100% is being reported for those pictures just very similar. It's only the filter that isn't filtering them out!

[ghost]

Really? It sound like a bug (even a regression). The filter in PE has been designed so that the 100% threshold really mean exact matches.

[ghost]

I could reproduce the problem.