My Mac (iOS 10.12.6) is running Parallels (v15.1.4) so I have a Virtual Machine of Windows 10 Home.
I have Dropbox installed and it shows like this on my Mac:

but it shows on the PC side like this:

That is, there are two folders on the PC:
Dropbox (\\Mac) (B:)
Dropbox
Only the second one has the Dropbox icon on it.
I'm not sure what's going on. The contents of the two folders on the PC don't seem to be completely identical and files don't always sync between them (or maybe I'm not waiting long enough?). Sometimes a file is visible on the Mac side and sometimes it isn't unless I manually copy it from one Dropbox folder to the other on the PC.
I worry about the folders not being in sync (and what is being saved on Dropbox.com and what is not??) but I mostly want to know - am I using twice as much space on my local hard drive than necessary?
Any help to understand what is happening would be appreciated.