Update your iPhone, iPad or Mac to iOS 16.4, iPadOS 16.4 or macOS Ventura 13.3 to have the Photos app detect duplicates in your iCloud Shared Photo Library.
iOS 16.4’s Photos app detects duplicates in your shared image library
iCloud Shared Photo Library
macOS Ventura drops with Continuity Camera, iCloud Shared Photo Library, more
Some of the new macOS Ventura features include Stage Manager and Continuity Camera, which lets you use an iPhone as a webcam for your Mac.
Apple’s new iCloud Shared Photo Library feature appears in the third beta of iOS 16
The third betas of iOS 16, iPadOS 16 and macOS Ventura add Apple's new iCloud Shared Photo Library feature that was previewed earlier at this year's WWDC.