I have heard of adult Hoffmannius spinigerus being kept communally.
Scorpio maurus are often thought of as communal species due to them sometimes being found in 'colonys' in the wild but in reality they don't like to share enclosures. When I tried it I very quickly ended up with one fat scorpion. With a large enclosure and luck you may have some success keeping them together.
Other than that there isn't really any non- Buthidae arid/desert scorpions that will live together that I can think of.
Anyone else??