Duplicate files · Removing and restoring duplicates
Will removing duplicates delete my files or lose data?
Short answer: No. One copy of every set is always kept, the copy you keep is re-checked first, and extra copies on your Mac go to the Recycle Vault — recoverable for about 6 months — or the Trash if no external drive is set up. Nothing is removed until you confirm.
No. At least one copy of every set is always kept — Storage Studio refuses any removal that would take the last copy — and the extra copies on your Mac aren't deleted outright: they go to the Recycle Vault, where they stay recoverable for about 6 months (or to your Mac's Trash if no external drive is set up).
Before removing anything, Storage Studio also checks that the copy you're keeping is still there and readable. If it isn't, nothing is removed and you'll see "The copy you're keeping couldn't be verified, so nothing was removed."
Cloud accounts follow the provider's rules: where the service has its own trash, removed copies go there; where it doesn't, you're asked to confirm a permanent removal on purpose. See removing cloud duplicates.