How so?
Even though you have a more specialized tool (which I don’t use, so you know more about this than I do), simpler methods might still work, or maybe this will just be a mystery until someone more expert helps…
One thing I will point out is that Duplicati is typically two processes, so make sure you watch the right one. Probably you want the child. The parent is the originally installed Duplicati (base version) which checks for updates on the drive and starts the latest version, which does the actual work. Uninstalling and reinstalling should fix the Program Files\Duplicati 2 base version though, and unless you had Duplicati run a later one, 2.0.5.1 is the latest Beta. There are newer Canary builds though, and they would hang around to be run…
Downgrading / reverting to a lower version shows where they might be (it varies depending on the install). Based on what I heard, I assumed there was no new update, but it might be worth checking to make sure.
If you want to avoid the double-process behavior, you can set an environment variable. An example of this:
set AUTOUPDATER_Duplicati_SKIP_UPDATE=true
If you want to confirm your file’s hash, here are some:
22fe5d4a42031f1b9f756b9b716b6180 MD5
b8d1ccb0c54e9af5ffe497fc328f07ab4260e4ad SHA-1
Sysinternals Process Explorer can show the loaded .NET Assemblies and the path assembly came from.