It was discovered during integration with Google Photos using java-photoslibrary, please see its details
com.google.photos.library
google-photos-library-client
1.7.0
For example, real test account has 468 files in Photos App, although Photos library returns 476 files. When the real list of files on Google Photos was compared with the list of files returned by PhotosLibraryClient.listMediaItems(), appeared that 8 files had duplicates, although there were no duplicates in Photos App.
To handle this issue on our side, we just wrapped result of PhotosLibraryClient.listMediaItems() to Set, although it'd be useful to see any comments about it in documentation, if it is expected, or have a fix for this issue.
Let me know if you need any additional info on it.
Thanks.