How do I remove photo duplicates after merging libraries, and fix USB import in Photos?

TheWorstAppleSinceEve wrote: … Unfortunately, the Photos app no longer imports new photos when I plug in my phone.

Have you tried Apple's Image Capture in the Applications folder. What has that done?

…now there are tons of duplicates. What is the easiest way to delete them?

There are Duplicate Finder apps in the App store. Whatever you do, don't let them mess with the Photos Library! And I'd make sure I had a backup of things before I let those things delete anything.

You could import the pictures into a new Library. Photos will avoid importing exact duplicates. But it won't look for pictures that are the same, but the same except for resolution, or file size, or such things. It avoids exact duplicates.

Once in Photos, the best app to search for duplicates, and to do many other useful things, is the trusted 3rd party app PowerPhotos ($35) 

p.s. …I don't need iCloud storage --

It sounds like maybe you do. iCloud's syncing is way more reliable and versatile. I wouldn't count on Apple to improve cable transfers-- I think that they are satisfied they've found a better way.

I bought a Macbook to do two things: browse the internet, and store my photos on my hard drive, so I have plenty of HD storage space to do so.

Then it sounds like just what iCloud does.

Apple's Photos 10 has a built in duplicate detection feature and you can merge the photos so you have just one copy of the image. However, it does take a while to scan and compare all of the photos in a library, sometimes up to a week or more.

If you want to be more proactive in deletion consider this: you want an app that will identify the potential duplicates, put them in an album or mark them with a keyword for easy retrieval and deletion by you. You don't want one that does the deletion itself for obvious reasons. 

I've run tests on the these two apps with the following results and found them to be safe to use:

PowerPhotos - $30  

PowerPhotos is the iPhoto Library Manager version for Photos and is very powerful. Although more expensive I would recommend it as it has more capabilities than the others like the capability to merge Photos libraries or copy photos, both original and edited versions, along with their metadata between libraries.

PhotoSweeper - $15 - Demo version available.

PhotoSweeper compares bitmaps and/or histograms so it can detect duplicate images even if they have different file sizes, file names, image sizes and capture dates.

PowerPhotos does a better job of merging photos from libraries that the current version of Photos. The following is a comparison of PowerPhotos vs Photos for merging libraries:

I ran a number of tests with a 3119 photo, 72 video and 97 keyword Photos library with keywords, captions, keywords and locations.  I merged it into an empty library using Photos and PowerPhotos.  This is what I found was imported by each;

PowerPhotos:           Photos:

Albums***                                          -----------

Smart Albums (as regular albums)** -----------

Folders Containing Albums -----------

Captions                                             Captions

Titles                                                   Titles

Keywords* Keywords (some but not all: …

…see Note *)

Original images                                  Original images

Edited images                                     Edited images

---------------                                        Locations

Favorites                                             Favorites

Can detect and exclude                      Duplicates

duplicates upon import or not

Neither method could import/merge projects. 

Both methods could import older iPhoto libraries into a Photos library when the iPhoto library couldn't be migrated into a Photos library. 

Notes:

*The Photos app only imported 84 keywords our of 97. PowerPhotos merged 147 keywords. Photos only imported keywords that were embedded in the original file and not those added by Photos. PowerPhotos imported all of them.

**The original library had 90 Smart Albums. All were merged by PowerPhotos but, as indicated above, the Smart albums were brought over as regular albums. No album of any kind were imported by Photos. Also only PowerPhotos imported folders.

The original library had 34 regular albums and 1 folder with some nested albums. PowerPhotos merger all of them successfully.

The original library had 72 videos. Photos imported only 57. PowerPhoto got all 72 in its merge.

Where is your Photos Library? If it's on the external, what format is that?