I'm a new user.
I ran De-Dup against my ~200MB iTunes directory; it found 1800+ verified exact duplicate files.
It at first froze after beginning de-duplcation, then on re-run, crashed with a crash dump.
Windows 10, professional, new PerfectTUNES installation, naive user.
I post this in case it's useful to development and debugging.
The Manage Attachments, interestingly, does not permit attachment of a .dmp file created by the software, and the filesize of 137 exceeds the fileesize limit of 100 kb