Important question about subs

[Mystic Pymp]

I've done some research and apparently it IS possible if tracks have the same bit rate and same exact number of samples in them, and they might since they come from the same subless track with additional layer of subliminals. It's still bizarre for me, but there are formats like this (take simple .txt file) where size depends on length only, not the contents. Even more bizarre for me is that they have same sizes despite different tagging, which must have add a couple of bytes of difference. But perhaps tagging work same way as names of folder paths work and are not stored on the file itself?

TL;DR Same sizes of the files don't prove anything against Shannon's subs being legit.

I'd love to hear about some technicalities from someone knowledgeable though, out of simple curiosity if anything else.