Many years ago I asked my reptile vet if my beardies and tortoise could be housed together, after all there husbandry was almost identical and i have heard of others doing it? he gave me some very realistic advice, he told me that many reptiles carry parasites or bacteria which is not dangerous to them because their immune system can control it but to other species could be agonizing if not deadly. Many of these animals come from different areas and have evolved to control certain ailments but diseases/parasites from other areas which the species has never been exposed to could ravage there systems. He recommended never to mix species no matter how safe it may seen to us. Vets see all the problems that arise from these situations and know this can and does happen.