can i find and eliminate duplicates in Photos?

Yes. These applications will identify and help remove duplicate photos from a Photos Library:

• Duplicate Annihilator for Photos - $7.95
• PhotoSweeper - $9.99 - Demo version available.
• PowerPhotos - $29.95
• Photos Duplicate Cleaner - Free

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 along with their metadata between libraries.

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

I think you'll be happy with PowerPhotos. It is an excellent browser of Photo libraries with a user selectable background color, white to black, and any two user selectable metadata fields beneath each thumbnail.

Now I just have to decide and then execute

I rarely use PowerPhotos to search for duplicates, but I could not do without it. I need it to sort photos by size or by filename, or as a second browser window, when working with Photos.

It will depend on the kind of duplicates you are looking for, Are your photos exact duplicates - the same file imported multiple times, or edited versions of the same photo? If you imported different versions of the same photo, then you will need Photo Sweeper.

In all other cases, I second OT's recommendation of Power Photos.