They're the files you downloaded from servers.
You can't activate them since they are cached files or just simple folders
Any way I got the Map "Flatlands" 2 times, and it appears on map list when I didnt even download it?
Sometimes if there isn't stuff like Textures, Sounds etc. RTB automatically downloads it as a .zip file so that it's just faster and makes no difference whatsoever.
The only way that could happen is if there's a server.cs file in one of the folders, and those aren't downloaded when you load the addons in a server.