A Suggestion For The Duplicates Tool
I used Google Takeout to download all my pics and then used immich.go to upload them all into immich (i believe any way photos get loaded wouldn't matter with my suggestion).
After the duplicate finder job ran I started going through photos and cleaning them one by one off the computer. Got comfortable enough I was removing the right ones I set my "camera" folder to backup within immich on my phone.
This started to backup 100 or so photos to immich and I proceeded again to delete duplicates from my computer. Got to a point i started noticing I was deleting the same pictures over and over and could not figure out why.
What I later found out was i was deleting copies created by the backup process which just so happened were a duplicate picture from the original photo load. Makes sense because if you are using Google photos your camera folder will have many pics that will be loaded in Google photos as they only go away when phone space runs out.
My suggested for the Dupes Tool would be showing the "device Id" as in my case was my computer mame and a random ID being my phone. Would be helpful for the tool to suggest keeping the photo that is being backed up by a different device as well.
Hope this may help others or the development team
So far great app