I would like a feature to use multiple installation folder. In that way I could use multiple drive in my PC.
Ther's should also be a feature to move game data from a drive to another.

Yes! But at the very least, the specific platform would have to allow that option on their settings to begin with! (remember, the installation for other platforms' games are done entirely through said platforms, not through GOG Connect).

But, for example, as far as I know, Steam can only let you add a new downloads folder *if* it's in another drive. Then, even then, GOG Galaxy would have to be aware of the setting changes inside those specific platforms, which would probably not be possible.

All that said... for *GOG games*, sure, that's something they could implement as a feature (there's... something about it the settings -> 'Other downloads folder', I don't think that's it). A "workaround" atm is, of course, to bypass GOG Connect entirely and download the games manually, then move their files to wherever you want.

(not sure this post made sense enough, haven't had my coffee yet :) )

its possible with normal Galaxy (1 or 2) you just install a few games then change the default install path and install some more... Gog remembers where the games are

Steam does allow something along the same lines but the default documents folders are hard to move and some games [like Stellaris] will stop working if you move this folder because the multiplayer assumes that spot

Hope I'm posting this in the right section, apologies if it's not.

In my C: drive, there is a folder, GOG Games, where my games are installed. But in the Program Files (x86) folder, there is a GOG Galaxy folder, where apparently the games are ALSO installed.

A few questions: First, out of curiosity, how did I end up with two different folders for the same games? Second, I haven't done an in-depth investigation, but the individual game folder contents seems to be identical, with minor exceptions. Last, is is safe to delete one of the folders, and if so, which one to delete?

Thanks!

- you could install via offline installers to one folder, while via Galaxy to another.
- multiple users on PC.
- etc.

Also check folders' creation dates. You can select "Show folder" via "Manage installation" context menu entry.
Or ticking custom executables in "Configure" shows default location path.