I don't know if the server or cloud (If there is one) saves the dupes but if you want to keep all your game installations (GMod), just delete everything in "Steam" except steamapps folder.

And then move that folder back into the newly refreshed Steam replacing the newer steamapps folder.

I don't know if the server or cloud (If there is one) saves the dupes but if you want to keep all your game installations (GMod), just delete everything in "Steam" [b][u]except[/u][/b] steamapps folder. And then move that folder back into the newly refreshed Steam replacing the newer steamapps folder.