Duplicate files · Duplicates in iCloud Drive
Does removing a duplicate in iCloud Drive remove it from my other devices?
Short answer: Yes. Removing a file from iCloud Drive removes it on every device signed in to the same Apple Account; the copy you keep stays everywhere. The removed copy goes to the Recycle Vault (or Trash), so you can restore it and it syncs back.
Yes — that's how iCloud Drive works. Any file you remove from iCloud Drive on your Mac is removed from iCloud Drive everywhere, including your iPhone, iPad and other Macs signed in to the same Apple Account. The copy you chose to keep stays, and it stays available on all of them.
On your Mac, the removed copy goes to Storage Studio's Recycle Vault (or the Trash if no drive is set up), so you can restore it — restoring it to iCloud Drive brings it back on your other devices too.