A way to have Steam launch two different builds with 2 different modsets?

[solid wyvern]

For example, having build 41 to play with my friends, and having build 42 to play solo without having to redownload the old builds and resubscribe to all the mods.

[lunar canopy]

Copy the install folder of the game to another location, then swich the version on Steam

Now you have two versions, one in the folder you copied, one through Steam