In ~/Library/CloudStorage/ there are two directories: iCloud Drive, and iCloud Drive 2. The first one (just iCloud Drive) contains all my files and the creation date is when I bought my MacBook. The second is four days before the current time of writing.
iCloud Drive 2 contains 336 items; the names of my applications, followed by a number. They are obviously duplicates (I have TextEdit 14, for example), but most contain no files whatsoever. None of these duplicates show on my Desktop, but the sidebar favourite 'Desktop' points to the iCloud Drive 2.
In macOS Catalina beta 3,