adamdea
You are not a sound quality evaluation device
I am not at all convinced that anything has gone wrong with these files. It would probably best if you either correspond direct with Archimago or simply leave this until after the outcome of the test.Possibly, but for the wrong reasons IMHO, because it seems something has gone wrong with these files.
Firstly, they measure a bit depth of 24, which means they have never been converted (dithered or not) from 16-bit to 24-bit. As mentioned earlier, and equally by Werner, you should achieve a -98dB null. If using dither, you are likely to lose 10 dB or so (Adobe Audition), but the files will still sound identical to all intent and purposes.
Peter
It would be very unfortunate if it were necessary to analyse out exactly whether you were right or wrong. I am concerned that this may involve giving away or encouraging others to work out which file is which.