How can I efficiently remove a great many duplicate photos if there is no "Duplicates" folder in Photos sidebar?

DuplicatePhotos wrote:

So yes my Mac is OS 12.7

Steve

In that case 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 - $29.95  

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 - $9.99 - 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.

Personally, I prefer PowerPhotos as it is the best utility tool for Photos libraries.

Is the system version given below your question still valid? macOS 12.7?

The duplicates album is a new feature in macOS 13 Ventura or macOS 14 Sonoma. It is not yet available on macOS 12. If you are still running macOS 12 Monterey, consider to upgrade to macOS 13 or later, if it is supported on your Mac.

Remove duplicate photos in Photos on Mac – Apple Support (UK)

"What? I've never heard of anything taking a Mac weeks to process! "

The recent versions of Photos 8since Photos 5 on macOS 10.15 Catalina) are very ambitious and are using Artificial Intelligence to understand what our photos and videos are showing. Quite a few of the background processes in Photos are now taking a very long time to complete, if the library is large. You may want to look below the tab "days" while viewing the Library. are you still seeing an endless loop of "Curating best photos, detecting Duplicates, composing Layout, etc"? The Duplicates album will appear, once Photos has come across some pairs of similar or duplicate photos.And Photos will add to this album over time.

Can your Mac be updated to Ventura or Sonoma?

What kinds of duplicates are in your Photos Library? Do you have exact duplicates, the same image file or video file imported several times? Or are your duplicates slightly differently adjusted versions of the same photo or versions in a different file format or resolution?

I am asking, because there should not be exact duplicates in the library, only different versions of the same photo or similar photos. Photos is checking for already imported photo on import and trying to prevent us from importing duplicates. We have to import the duplicates intentionally to create exact duplicates in the library. Or we have to use a method of importing, that is breaking Photos's duplicate detection, for example mixing two different methods of importing or having the files automatically converted to JPEG on import.

The Duplicates folder only shows up when you Photos has scanned your Library and found duplicates. If you don't see the Duplicates folder (between Imports and Recently Deleted for me), then Photos hasn't yet detected any. That doesn't mean it won't. Finding duplicates is really hard--it can take weeks to find duplicates in even a medium sized Library! How long have you been waiting?

And, it's really hard! It will find some that look similar, but they're taken at slightly different times:

These were identified as duplicates, and you can see why. I also have duplicates that are different resolutions or crops where I want to keep both. And it can miss some. So, unfortunately, I can't expect it to do all the work form me.

Yeah--it's hard stuff. If you had a deck of 53 cards, how long would it take you to find the duplicate? How about 53 similar pictures? How about 10,000 pictures? And Photos doesn't want to do it while you're busy with your pictures, because that would slow it down so much. It looks for pictures that may have different filenames, different dates, different resolutions, but still look the same. It's hard.

So, when there is a lot of background processing to be done by Photos, we plug the computer in over night and leave it running, but we put another app (like a finder window) in front so Photos will be freed up to do the scanning.

While there are several apps that will scan for duplicates if they are floating free in the Finder, they will wreak havoc on pictures inside the Photos package. Beware!

Before Ventura introduced duplicate scanning in Photos, the program that most people used to deal with duplicates was PowerPhotos ($30-- they have trial versions). Using it works, but you've got to spend a lot of time with it. Another technique if you're looking for identical pictures with the same date and filenam: PowerPhotos can provide a list in order of date, and you can examine pictures taken at exactly the same time. And we still use PowerPhotos for all kinds of useful stuff.