You can take one or two-degree but not from one mode, if you are studying one degree from distance learning then at the same time for another degree you have to apply for regular mode. Earlier that system was different and the same person can take multiple degrees from the same mode at the same time, but according to the new policy, you cannot do this.
As you have mentioned that you are already pursuing two degrees out of which one is from regular mode and one from distance learning mode, so for now you can apply for a new degree. Once you have completed your MSc through Distance Learning, then you can apply for the next course.
One last piece of advice, our aim should not be just to collect degrees but the main aim should be to acquire knowledge. When you are already pursuing two difficult degrees, doing MBA simultaneously is not a good option anyway. First, complete one of the above with good knowledge and then select the next one.