possible bug with filenames with trailing underscore

[suppsuppa]

Hello,
I've having issues scanning dupes from subfolders, dupeguru is considering files with trailing underscores as dupes
For example 3 files named "filename.pdf" ,"filename_.pdf" and "filename__.pdf" and so on....

Options:
Scan by filename
Hardness 100%
All other flags disabled
(I think these options means an exact match on filename)

myfile1.pdf in subfolder1
myfile1_.pdf in subfolder2
myfile1__.pdf in subfolder2 (2 underscores here)

these files are marked as dupes, but I wasn't expecting that, they should have been considered 3 different filenames.

Screenshots
options:

results:

This on Win 10 latest version

Maybe I'm doing something wrong, please let me know.
Thanks