Using iCloud to sync between two computers

I have recently started using iCloud to sync my documents folder from a MacBook. I would now like to add my iMac documents to iCloud.

Previously, I had been using Google Drive to keep these two computers' documents folders in-sync.

So what happens when I move the iMac's documents folder to the iCloud folder? The files and folder structure should be pretty much identical.

Will I end up with duplicates of everything? Or do things get merged? Or is this not something iCloud is meant to do?

Thanks!