I'm going to say that there must be two differant dialects and they both spell it in a differant way?
I think I can take that as a correct answer. In fact there are two standard written forms of Norwegian, both in official use in Norway. Referring to the wikipedia article on Nynorsk, which in turn links to the article on Bokmål, gives one a fairly good picture. So this isn't a bilingual country in the sense that Belgium or Canada is. Even on trains and in other public places you might find notices in one, the other or both. I first noticed this while travelling by train in Norway. The signs for "non-smokers" were written slightly differently in two adjacent coaches.
Over to you now, Heinz!
And, by the way, Norge is Bokmål while Noreg is Nynorsk.