The first category is the Mac user who does not use Photos or iPhoto. The second group is Mac users who still cling to iPhoto. The third group is Mac users who have and use Photos. The fourth group needs multiple photo libraries.
Find. The. Dupes.
First, if there is a scourge that existed on my Photos (and iPhoto) library for years, and exists on the new Photos, too, it’s photo duplicates. Sometimes, especially after a hectic weekend of photo taking, an entire Photos screen of duplicates appears, and pruning is manual and tedious.
iPhoto Library Manager has been around for years and does what is not easily done in iPhoto. Manage multiple photo libraries.
For older Macs, iPhoto Library Manager is simple to setup and use. Create a new library with a click to the Toolbar at the top. There are options to Add a Library to iPhoto Library Manager, Remove a Library, find the Library in the Finder, and that includes options to Merge Libraries and Find Duplicates from within a library.
For anyone with an older Mac who finds photo library management to be too simplistic, and suffers from duplicate photos, this is the app to use. Here’s the problem. iPhoto is End Of Life. It’s been replaced by the more modern Photos library.
Fortunately, PowerPhotos works much like iPhoto Library Manager for Macs running Photos in OS X. Create and manage multiple photo libraries, copy photos and metadata from one library to another; even merge photo libraries. And, of course, you can find and delete duplicate photos.
Managing multiple photo libraries has never been as easy. There’s also good news for Mac users still using iPhoto but are not yet willing to switch to Photos. The license is for both iPhoto Library Manager and PowerPhotos, and the latter has an option to migrate both iPhoto and Aperture (also End of Life from Apple) libraries to Photos, which can be a cumbersome process.
What I like about PowerPhotos is the ability to search across multiple Photos libraries at the same time (a good reason to use keyword tags). Of course, both apps can find duplicate photos. PowerPhotos is so good it even recognizes the new Selfies and Screenshots albums in Photos.
Apple provides a built-in way to create and open multiple photo libraries in both iPhoto and Photos (press the Option key while click the icon in the Dock; you get a dialog box with options), but none of the bells and whistles in either of these apps. They’re so good you won’t find them on the Mac App Store.