The English and German versions of the game were developed at the same time. The German version was released first because the German publisher was in place fairly early (a couple years ago), while there were apparently problems with the English publishers (no official announcement yet; last we heard, a month or so ago, they were still finalizing stuff).
After the international release there may be an official patch to switch the text language in the game. I would guess that is why the English text is included in the German release, anyway.
