The 2017.06.06 version of Deduplicator for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The program lies within System Tools, more precisely File Managers. The actual developer of this free software for Mac is Bonhard Computing.
From the developer:
Simply paste your list into Deduplicator and hit ‘Find Duplicates’. Deduplicator will identify duplicate items and show them in a preview window. Hit ‘Remove Duplicates’ to proceed. Your list has now been deduplicated and contains only unique elements.
To account for variation in capitalisation and spelling, you may wish to use fuzzy matching.
You may want to check out more software for Mac, such as DataCleaner, Silent Sifter - Organize Photos or Strongsync, which might be related to Deduplicator.