Is training mma twice a day to much?

not if your Bruce Lee ;D

I don't think so but if your body starts to break down then you might want to consider having a day of rest after two days or working out or maybe on that third day just doing the Muay Thai. You will know if it is too much by being overly tired and feeling like your never being able to catch up on your sleep; being overly sore, aches, pains, and any cuts taking longer to heal and go away, and it easier to catch colds and other viruses.

The other thing you might consider and can do is to vary that workout in the morning and change up the exercises and calisthenics that you are doing so that you work those various areas differently on some days. That can be beneficial as well in helping to prevent your body and various parts of it from breaking down to occasionally do something like that.

That sounds like a kickboxing training than a mma training.

That's a good training schedule as long as you can get proper rest in between training and take proper rest days. Pros usually train two to three times a day usually classes and takes a nap to help with the recovery. They also have a well scheduled off day to make sure they don't over work themselves. Also eating well would really help with that amount of training.