Ok, one step to do is now clear.
As an option do you want 'case insensitive', what means 'upper/lower case does not matter'?
See there ...
Simple Soundex Calculator
... if you can adapt the 'Simple Soundex Calculator' to your needs.
(?) See there ...
... if you can adapt the 'duplicates finder' to your needs.
Once the true duplicates are known, you know the different files too.
Well, you can try other methods how to compare text data.
At first you can split the filename (artist - title) into two parts and store each part into one helper tagfield, e. g. 'artist' -> ARTIST_FN, and 'title' -> TITLE_FN.
In Mp3tag listview create two columns for the new tagfields.
Arrange the new columns beside the columns for the standard tagfields ARTIST and TITLE.
Sort the listview by the term %ARTIST%%ARTIST_FN%
Now you can visually detect differences between the tagfields ARTIST and ARTIST FN.
Apply the same method for the tagfield TITLE.
Also it should be possible to compare the complete filename against the combination of ARTIST and TITLE.
Sort the listview by %_FILENAME% and compare the 'filename' data with the 'artist-title' data.