If your iPhone is running iOS 16 or a newer version, you do not need a third-party app to merge duplicate photos. What Happens When You Merge Duplicate Photos? When you merge duplicate photos, your iPhone:Keeps the highest-quality version of the photo. How To Merge Duplicate Photos On iPhoneThe built-in Duplicates feature is the easiest and safest way to clean your photo library. How To Merge All Duplicate Photos At OnceIf you have hundreds of duplicate photos, merging them individually can take time.