Running League on Multiple users (2 gaming rigs 1 cpu)

Unique question but does anyone have information about why we can't run already 2 leagues from 1 pc I'm using the program ASTER which been used to run two user accounts from one PC with 2 monitors and run like 2 gaming rigs before i was using it to play league with my friend using my dedicated GPU and External GPU to run (2 PCS from one CPU) and it was working like butter but now it just give me Critical error. Running 2 steams 2 cs go 2 heartstones and every other game without any issue just league start giving me this error after the new client came out