There are those who are known to be communal like P.imperator,some Heterometrus, mesobuthus and Centruroides spp. to name a few,but as kejser wrote,its no garanty for one scorps wont suddently eat another roommate.Then there are "not normally communal" scorp but despite that,some have succes with keeping them together anyway..I think it depends much as how they are kept and from what instar.