How can I delete duplicate photos after update?

Updating to photos does not cause duplicates - what specifically did you do and what are you seeing?

Neither iPhoto nor Photos has a feature to find duplicates - Duplicate Annihilator or FatCat software's PowerPhotos do

LN

Photos has no tools to remove duplicates automatically.

It might be easier, to do the migration of your library again.

Where are you seeing the duplicates? You have only duplicate photos in the library, if they are duplicated in the Moments and not in the albums. You may be seeing the same photo in several albums, without actually having duplicates in your library.

Currently there are two apps that can search, help identify and assist in removing duplicate photos from a Photos library:

PowerPhotos - $129.95

Duplicate Annihilator for Photos - $7.95

PowerPhotos is from the developer who offers iPhoto Library Manager, the best and most versatile iPhoto utility offered. Those who purchase iPLM also receives a license for PowerPhotos or you can purchase a separate license for PowerPhotos alone. PowerPhotos will eventually include most of the features now found in iPLM, merge libraries, copy albums and moments between libraries while including keywords, titles, descriptions, locations, faces, etc.

You can use the Demo version of it to see how it works and accesses the images in the Photos library. It does a better job of displaying metadata the Photos does.

Currently there are two apps that can search, help identify and assist in removing duplicate photos from a Photos library:

PowerPhotos - $129.95

Duplicate Annihilator for Photos - $7.95

I believe that PowerPhotos is $19.95 - your fingers may be getting a bit "fat" 😉

LN

Obviously you don't speak or read typo. 😝 Yes, it's only $19.95. Thanks for the catch.