Those do you treat this file as the simplest/ordinary file on the disk?
In theory, its analogue should be Alternate Data Streams!
Those copy/move operations only apply to its contents, not to the file itself!
Those if we select this file and copy it, then we copy its contents to the same file in the target panel!
And if it's not there, we create it. The same is true for moving!
The only thing is that - if ordinary ones are also selected along with this file - then we analyze its contents in intersection with the selected files and the copy / move operation is performed only for those lines in this file that correspond to the result of the intersection. Those if for example 10 files are selected + in this file there are comments only for 2 of them - then when alongside with operation of 10 files copying - the comments are copied AND FOR these two files ONLY. The same goes for moving. ONLY two comments from this special file are moved! Not the whole descript.ion file!
Thus for your scenario:
Scenario 1: Copy comments with files is checked.
Result: Total Commander copies the 50 files, and copies also the comments of the 2 files which have one. You now have 82 comments on the right.
Scenario 2: Copy comments with files is NOT checked.
Result: Total Commander copies the 50 files and the comment file. Now you only have 2 comments on the right because the old comment file was overwritten.
1) We copy 50 files from left to the right. Now right panel contains 50+100=150 files and descript.ion file with 80+2 comments.
2) We copy 50 files from left to the right. Now right panel contains 50+100=150 files and descript.ion file with STILL THE SAME 80 comments!