depends on the program and university. It's fairly common to have a major and a minor that are only roughly comparable to the American equivalent. Having a double major? Impossible no, but probably pretty difficult with the new bachelor system.
I am not familiar with those universities or know much about those type of programs but I would think that it could turn out to be fairly hard. If it's a bachelors-program they are probably not the most organized (which is still the case with most German universities). If it's possible it'll probably mean that you have to stay an extra semester or too. Why don't you contact those universities/go on their websites? It should say whether they allow double majors in the first place.
I went to the websites but I couldn't get a clear answer .there are links for more information but all of them are in German and I am not flunet in it yet .I am really starting to second guess my Decision to study in Germany .