Usually you'd use the main bot to run a profile, then the follow bot to use Combat Bot routine, the routine can error at times, and cause the client to crash when loaded in the menu. I would assume running 2 bots would be much more stable then trying to run 4 (which I have done) and within a run, one would have crashed.
You would need to turn off any inactivity timers, as well as any unstucker you may have, as they'll interfere greatly.