how do i delete picture dublets on mac

Are you in fact running  macOS 12.6 Monterey as your signature says?

Are you talking about the Photos app? In Ventura (the upgrade OS after Monterey) Duplicate Finding became an integrated part of Photos. So you may want to upgrade.

Before Ventura, many of us used PhotoSweeper ($10), or PowerPhotos ($30) which does many more things. Be very careful about other apps that may corrupt a Photos Library.

There are apps which work for finding duplicate files in Finder, but they will mess up a Photos Library. For instance, I used an app called Gemini 2 for duplicate pictures I found in folders from old backups, but I would not use it with Photos. You can find other apps at the App Store.

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 - $13.99 - 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.