Confirm the images are local, accessible, and inside the selected folder. Check Settings → Scanning → Similar Photos and lower the minimum only when needed.
Similarity is an algorithmic comparison, not an identity test. Crops, rotations, edits, exposure, format, and resolution can change grouping.
Use Duplicate Files Finder for exact-content copies. Review every visual group manually before removing anything.
For a likely incorrect result, preserve the images and report their formats, dimensions, sizes, and redacted examples when you are comfortable sharing them.