How to remove duplicate photos in the new PHOTO app on OS X 10.10.3?

Question

macOS

Since the last update, iPhoto has been replaced with Photos.
At the first boot, something was automatically rebuilt there, all uploads / downloads from all apple devices via iCloud went through.
But now there are quite a lot of duplicate photos.
How to clean them? What program?

Answer 1

Gemini by MacPaw.
macpaw.com/en/gemini

Answer 2

here is an example of such takes - take.ms/7KUYL