You can run more than 1 RiD bot on a single RID account as long as it is not more than 1 of the same bot, ie you cannot run 2 instances of PC on a single RID account. I also advise against making multiple accounts as the system would pick that up (if you are botting on multiple accounts with the same bot) and both accounts would be banned.
You can also try Simba and run multiple bots as well, they have no limit that I am aware of.