Can you do a Bachelor and Masters degree at the same time? Please read on...?

I'm finishing up a degree in Neuroscience at the moment. I really want to do a degree in astrophysics as well but that would mean starting all over again which no one thinks is a very good idea because my neuroscience degree would in effect go to waste. I want to go abroad to study and in Germany a neuroscience masters is available to be taught in english which would be awesome. What I want to know is if it would be possible to start a masters and a bachelors degree in the same year at the same university or if I would only be allowed to do one at a time?