Hi deceneu, i´m sorry - i´m not a native english speaker so probably you´ve misunderstood what i´ve wanted to say:
- of course all of this cities exists - i´ve never doubted this - there are even many cities called Hanau, Neustadt or Neuburg in Germany / Austria
cause of that fact these additional specifications have been added to the city names so you can differ them - like "Oh, you come from Neustadt in Holstein. I come from Neustadt an der Weinstrasse." So for example "Neustadt in Holstein" is the official city name, BUT most of the time everyone will call it just Neustadt if there´s no doubt about which Neustadt he´s talking about. Cause of that - from a domainer perspective Neustadt.com Hanau.com and Neuburg.com would be MUCH better names. Also "Neustadt in Holstein" and "Neuburg an der Donau" are very small cities, Hanau am Main is a small-medium city. I don´t see much value in this names. Perhaps you can try to sell them directly to the city authorities.