Duplicates in Photos library

Remove duplicate photos in Photos on Mac

You can easily remove duplicate photos and videos from your library. Duplicates appear automatically in the Duplicates album in the sidebar. (Depending on the size of your library, duplicates may take some time to appear as Photos analyzes your photos.)

Open Photos for me

1. In the Photos app on your Mac, click Duplicates in the sidebar.
2. Select the duplicates you want to merge.
3. You can select individual items in a single row and merge them or select multiple rows of duplicates and merge them all at once. A single original photo or video is kept from the selection in a row and other duplicates are deleted.
4. 
5. Click Merge [number] Duplicates.
6. One original photo or video appears where the selected duplicates were located in your library. Deleted duplicates appear in the Recently Deleted album where you can recover or permanently delete them.

Q - " This is a great feature that Apple should have had years ago, but thankful that it is there now, but I am noticing one problem. When I choose the "merge" command it does not actually do what it says it will do. "

A - Then have a few suggestions ;

1 - Get Support Choose a product and we’ll find you the best solution.Start now and open an Apple Support Ticket as they are Apple Employees to deal will these types of issues . 

2 - Product Feedback - Apple and make it known to Apple regarding this ongoing issue

This is a great feature that Apple should have had years ago, but thankful that it is there now, but I am noticing one problem. When I choose the "merge" command it does not actually do what it says it will do. Here is the issue: the command states that "Merging will keep one version of the duplicates that combines the highest quality and relevant data, and move the rest to Recently Deleted" -- the problem is that it does not always select the highest quality image. When it selects between two photos it always takes the lowest size image even when all the other factors are the same. This can happen when you import two different ways from a camera or web service like Google photos -- one more compressed than another and all else is the same. I want to keep the larger image. It only seems to do that when there are three photos. Seems like either a bug or Apple is making a storage decision that users cannot change. That is awful since I have lots of photos where there are lower quality images and thumbnails that I do not want to keep.

Am I missing some option -- there is nothing in the preferences about this, but I know that Apple frequently uses the option key to hide things.

Provided my feedback. Only difference I can see is that the extension is ".jpg" when the file is larger and ".JPG" when the file is smaller.