If you have been plagued by many duplicate files making a mess of your computer's iCloud Drive, help is at hand. Duplicate Sweeper can scan your iCloud Drive and return a list of all duplicates files that it contains. It then makes it easy to select which duplicate files to keep and which to remove - then remove them for you.
Since you have found this article, it is likely that you'll already have iCloud Drive set up on your computer. However, if you still need to set it up, you can find instructions on how to do this on Apple's website here: https://support.apple.com/en-us/HT201391. As you can see, you need to download and install iCloud on your computer, then enable iCloud Drive.
So, you've got iCloud Drive on your computer, and it's full of duplicate files. This is a problem for many, as you only get so much cloud storage space for free, and you don't want to be paying for extra storage if you can save space by deleting duplicates!
Double click the icon to start Duplicate Sweeper and hit "Add Folder". To sweep the whole iCloud Drive for duplicate files, select the iCloud Drive folder (by default, this is located in your user folder area). If you don't wish to scan the entire drive, you can open the folder and instead choose a sub folder or folders. Click OK to add the folder/s.
Next, click the "Start Duplicate Search" button in the top-right corner of Duplicate Sweeper.
Duplicate Sweeper will now scan the folder/s and return a list of any duplicate files it has found. You can manually tick the files in each group that you wish to remove, or press the "Keep All Newest Files" to automatically select the oldest files to remove. More selection preferences can be found under the Duplicates tab of the Duplicate Sweeper toolbar.