Iv had a whole boat load of different shards installed on my PC at once, but I had to install in different folders in the program files folder. I was never able to figure out why I could not have two of them running at once even though they are different programs in different folders
There are ways to tweek the opening of multiple URU sessions. Some on internal clients (it should maybe be something doable on normal external clients) just run batchtes to load multiple sessions of URU on 1 computer. Don't ask me how, I'm still NOOB on that but Michel aka Mister Magic is running MagicBot, MimiBot and himself all at once on a PC with Windows Operating System.
Maybe someone more techy can teach you how to do that.