From what you said in the email thread, I doubt the Duplicate Finder is involved in the crash. It sounds more like a problem due to a shell extension or video codec corrupting the process and causing it to crash, or possibly a bug in 10.0.3.4 itself (e.g. there were slight changes to the MD5 code, though nobody else has reported problems so far), potentially triggered when certain files/folders are encountered and processed by the shell extension, video codec or Opus itself.
For tracking that sort of thing down, see these two guides:
Crash, exit or high CPU usage when viewing certain directories:
Crash, exit or high CPU usage when right-clicking certain files:
The first seems more likely, from what you describe, but it's possible the 2nd is also relevant. e.g. If the crash only happens sometime after you right-click certain files or types of files, due to a problem that doesn't always cause an instant crash but corrupts something which later causes a crash.