Hail to the king, baby!
German censorship regulations for video games are notoriously strict and strange more often than not. Games like the original Quake and Doom are treated much like pornography when it comes to advertisement and distribution. Duke seems to have slipped through a crack wide enough to allow for a release of the 20th Anniversary World Tour Edition.
The Steam version of the game is available in Germany since late last year, but a lot of restrictions remained in place for the console versions of the game. These seem to have been resolved now.
It will be interesting to see how the Bulletstorm: Full Clip edition fares with censors in a months time. Bulletstorm's blood and gore have been heavily toned down for the German market during the initial release and Duke will also be making an appearance in the Full Clip edition.