As long as proper husbandry is kept, and feeding is done safely, it's usually fine. That is, of course, after a given ammount of time for quarantine. Of course it would always be best if you kept them separate all their lives. But sometimes it's a judgement call. When you're dealing with animals such as leopard geckos, you need to consider each one as though it has crypto and will instantly wipe out you collection. Because that happens all too often. But with ball pythons the dangers are there, but less likely to occur. If you have CB animals that you've had for years with no problems, it's pretty safe to assume it would be ok. But even with new animals you need to keep a close eye on them. It's a judgement call really.
