Some people can successfully keep Androctonus spp. together, but as Connie said, it helps to remove any established territory by mixing the substrate around and rearranging everything.
If there's fighting, keep them separate.
Species that fight will know to mate when the time is right. When they mate, the male grasps the female's pedipalps (pinchers) and they "dance" (there may be some stinging, but don't worry).