SilverBlueMedallion
File is here:
https://www.dropbox.com/s/bk7e8dye57eq1u8/Retroheart.cwp?dl=0
here are the duplicate events:

Okay, I opened your project.
If I select the entire track, undupe deletes 10 duplicate events.
If I select ONLY these two duplicate notes (F#4), undupe does not delete anything. This is because, as I said in my second post of this topic, there is a bug in the undupe, which needs to have
at least one selected note BEFORE the desired selection.
So, if I select (at least) the previous note (F#3), in addition to the two desired (F#4), undupe will correctly detect and remove the duplicate second note (F#4).
So
I could sentence two conditions for undupe.cal to work properly:- Make sure all selected notes are in the same clip (or make a bounce to turn everything into a single clip);
- Make sure that at least one note (which is not duplicated) is selected before the desired selection range.
I think if you can get by with this little bug, you will not have any more problems.