Why Does My Photo App Show Two Copies of Every Picture?
Duplicates after a Takeout import usually mean album folders, edited versions, or a second import. Here is how to tell.
Three causes, and they look identical until you check.
Album folders. A photo in three albums appears in three folders, so importing the whole export brings it in three times. Edited versions. If you edited a photo in Google Photos, the export contains both the original and an -edited copy. A second import. Running an import twice into an app that does not deduplicate gives you two of everything.
The app handles all three. It can skip photos that already exist in your destination rather than copying them twice, and it knows the difference between an original and its edited version so you choose which one to keep. Run it into an existing library and it adds only what is genuinely new. The first 500 photos are free, so you can test the behaviour on one album first.