No, it's still possible. You just need to find other ways to supply your servant. You can't do it yourself (Easily), so their stats are going to be nerfed simply from lack of prana. You're an anchor, not a full on Master, despite command seal. So yes, you can have a master from Atlas. It just isn't as easy to do so.
As for the double master, you need someone willing to do that with you. Just saying.