Image each stick first, then do all the sorting on the images. Old flash dies when you read it over and over, and the Arch wiki's recovery page says to work from images, not the device.
1. Make an image: sudo ddrescue /dev/sdX dad-01.img dad-01.map (the map file lets it resume and retry bad spots)
2. Mount it read-only: sudo mount -o ro,loop dad-01.img /mnt/dad01
3. Once every stick is mounted, find duplicates across all of them:
rmlint /mnt/dad01 /mnt/dad02 ...
rmlint never deletes anything itself. It writes an rmlint.sh you can read before running. jdupes -r does the same job and checks byte by byte. rdfind ranks the copies by the order you list the folders, so put the folder you trust most first.
4. Copy the unique files to your real disk, skipping .cache, .mozilla and .thunderbird/*/Cache.
The lost+found files are pieces fsck saved, named #12345 with no extension. Run file on them (file /mnt/dad01/lost+found/*) and you'll often find JPEGs and documents. If whole folders seem to be missing, photorec dad-01.img can carve files out of the free space too.
