Google-photos – Deduplicate Google Photos photos

If you have the Google Photos saved in your Google Drive, you should be able to install the Google Drive for Mac / PC to get the folder 'mounted' on your computer.

Google Drive Installer

From there, you can use an application such as dupeGuru (which works on Mac and Windows). You should be able to scan the Google Photos folder within your Google Drive and find the duplicates.

dupeGuru Actions -- Do whatever you want with your duplicates. Not only can you delete duplicates files dupeGuru finds, but you can also move or copy them elsewhere. There are also multiple ways to filter and sort your results to easily weed out false duplicates (for low threshold scans).

dupeGuru