I use Duplicate Cleaner Pro 3.2.7 for file deletions on a Windows machine — a complex programme that requires care in selecting the various options. Gemini is MUCH EASIER to use. The only option available is to check for EXACT MATCHES. That way one can make deletions with confidence that one has at least one copy of each file that had duplicates. Other Mac programmes can look for close matches, but these requires care to make sure that one is deleting the right files.
BBoeckel about Gemini: The Duplicate Finder