Photo app version 11.0 (831.0.014) - Duplicate

Tikra wrote: …That is a pity, that apple isn"t able even to mark those who are really double and those being nearly identical.

I agree-- and I don't know why they don't make the distinction. You can leave feedback for Apple here:

Feedback - Photos - Apple

I have.

.... are there any other tools in the market doing this job better.

There are many, but I wouldn't trust most of them. Letting a random app mess with a Photos Library can lead to corruption. There are a couple, however, that we know people around here trust.

The best choice is the trusted 3rd party app PowerPhotos ($40,) which does way more stuff than duplicates! PowerPhotos is essential in handling multiple Libraries, for instance, and it adds lots of enhancements to Photos.

For duplicates you can control the requirements for a match.

You get choices:

And you can choose rules for automatically choosing Similars, if you wish:

Or you can leave it on Manual Choice.

PowerPhotos has a free trial version, but I'm not sure what the trial restrictions are.

Another app that people trust is PhotoSweeper ($15 or $1) which is cheaper but does only duplicates. PhotoSweeper is also available as an iPhone or iPad app. I haven't checked this in a long time-- I know it's trustworthy, but I'm not sure of it's was of use, now.

Let us know what you think…

In the Utilities/Duplicates album, Photos recognizes both Exact Duplicates and Similar Duplicates. Similars may have different resolutions, different sizes, different metadata-- but they look pretty much the same. Sometimes, though, Similar duplicates are really different pictures, like this pair:

and I want to keep both! So with Similars, you need to be very very careful.

Even with Exact Duplicates, the metadata may be different, so I usually copy the Keywords back and forth, and I try to give both the same Caption information and same Titles, so the one that's chosen will have all the all the information from both.

With Exact Duplicates (after careful examination,) Merge is a good choice-- it puts the chosen one in all the albums that either of them were in. That's a real hassle with duplicates-- if you have one picture of Aunt Ethel in the Grand Canyon album, and a duplicate in the Oct 2018 album, then deleting one of the duplicates removes it from an album that should have her picture. Merge will remove one and fill the empty spots with the chosen copy.

So, I think the answer to your question, "do I have to be cautious?" is YES, you sure do!

There is some salvation, though, in that if you delete the wrong one, or if Merge deletes the wrong one, the loser goes in Recently Deleted, and you have 30 days to change your mind.

léonie wrote: …The only exact duplicates in my Photos Library are the duplicates I created intentionally by duplicating a photo, so I can use the same photo twice in a slideshow.

I don't much get "exact" duplicates, anymore. For those two surfing pictures that I showed as duplicates:

the second one was created so that it could have a different title, and so a different order, in a slide presentation.

Tikra wrote:

That is a pity, that apple isn"t able even to mark those who are really double and those being nearly identical. I have +/- 15000 pictures to be controlled (that's a lifetime work :))) .... are there any other tools in the market doing this job better.

Perhaps Apple did not include this feature, because it is unlikely that there are exact duplicates in a Photos Library. The Photos.app is checking for exact duplicates on import, and we have to confirm, that we want to import a duplicate to be able to import it. The Photos.app is also checking for duplicates when merging Photos Libraries in iCloud. The only exact duplicates in my Photos Library are the duplicates I created intentionally by duplicating a photo, so I can use the same photo twice in a slideshow.

on PowerPhotos.