Duplicate files · Duplicates basics
How does Storage Studio decide that two files are duplicates?
Short answer: Only files whose full content is identical are treated as duplicates. Names, dates and folders don't matter, and similar-but-different files such as two edits of one photo aren't flagged. Cloud accounts are compared using the provider's own content fingerprints, so nothing is downloaded.
Two files count as duplicates only when their full content is identical. Names, dates and folders don't matter — a file called "Invoice.pdf" in Downloads and "March invoice.pdf" in Documents are a duplicate set if their contents match exactly, while two files with the same name but different contents are not.
We don't publish the details of how files are compared, but here's what it means for you: on your Mac the whole content of each candidate is checked, not just the start of the file or its size, so a set only appears when the copies really are the same. In cloud accounts, Storage Studio uses the content fingerprints your provider already keeps for each file, so nothing has to be downloaded.
Similar-looking files — two edits of the same photo, or a song in two formats — aren't exact copies, so they're not shown.