Duplicate files · Where it looks and what it skips
Are files compared across my Mac, iCloud Drive and cloud accounts?
Short answer: No. This Mac, iCloud Drive and each cloud account are checked separately, and copies are only grouped within the same place. The same file in two places is often a deliberate backup, so it's never treated as waste.
No — each source is checked on its own. This Mac, iCloud Drive and every cloud account produce their own list of duplicate sets, and a file is only grouped with copies in the same place.
That's intentional. The same file in two different places — your Mac and a cloud account, or two different cloud accounts — is very often a deliberate second copy, such as a backup. Treating it as waste would risk removing the very copy you were relying on.
Within a single source, though, every copy is found, whichever folder it sits in.