To delete duplicate Google Photos using Files by Google, follow these steps:
- On your Android device, open Files by Google.
- Tap Menu Clean.
- On the "Duplicate files" card, tap Select files.
- Select the files you want to delete.
- At the bottom, tap Move x file(s) to Trash. (Reference 1)
- On the confirmation dialog, tap Move x file(s) to Trash. (Reference 1)