I am doing a Ph.D. in a university in New Zealand. I started 3 months ago and am about two years away from finishing. Since they do not issue visas (due to the pandemic), I had to start online and paid one year of tuition. For the next year, it looks like I will have to do the same thing. 

Now I got admission to a different PhD program in a slightly different subject in Europe with funding. Can I study for two PhDs at the same time? I am confident I can handle the workload (already finished much of the work for the NZ program). I am not asking whether this is a good idea, just whether it is allowed / legal.