Patch 3.1 – we’ve been waiting for it.

Krosh
Um... how are you going to have two versions on your computer at the same time? Naturally, as with everything else, if you update, then a "rollback" is only possible by deleting the game.

It's very simple, if you have enough space on your disk. Before installing any patch, I always make a copy of the old version, just in case. However, in this case, it's not difficult to reinstall the game if you haven't installed a huge number of mods.