Because there is no “link” between these audio files. Nothing indicates that they belong together.
Dual mono is an “invention” (read:workaround) from early PT systems because their audio engine could not handle stereo files. There is no other reason for that.
What’s the option “Stereo” in the Pool’s “Convert fIles”-window for then?
It does exactly what it says it does: converting the file from mono into stereo. Which will result in the information being copied into two channels.
The make “stereo from multi-mono” is a mixdown, merging, bringing together of two files.
HTH
Fredo