Feasibility of enrollments in a Masters program at one university and a PhD program in another university Is it possible to be enrolled at a Masters program at one university and a PhD program in another university?

Is one allowed to  do this? Or is this not possible in general?
Maybe, but why? Different topics? 

In any case, you'd have to check the rules of both universities. 

As a supervisor/employer of PhD students, I would not want my student doing this. A PhD is a full-time job, requiring full-time commitment. Financing is scarce and I wouldn't want to waste it on someone who is not fully committed.