According to a page on the official Duke Nukem site, the upcoming downloadable content also adds four fresh multiplayer maps to Duke Nukem Forever:
'The Doctor Who Cloned Me' includes new enemies and weapons
Sky High: The alien-infested corporate offices of Pooty, Inc. near the center of Las Vegas. This map includes three indoor floors taken over by the aliens and two rooftops, jump pads, stairwells, and building-to-building combat.Duke Nukem Forever 'The Doctor Who Cloned Me' will be available on December 13 for the PC, PlayStation 3 and Xbox 360 for $9.99 (800MS Points).
Command: EDF command center with an imprisoned BattleLord at its core! A two-level map featuring winding stairs, straightaway corridors, and jump pads.
Drop Zone: Rooftop of Duke’s Lady Killer Casino featuring indoor and outdoor combat and stairwells for platforming, an EDF dropship on landing pad, and a bottomless pit.
Biohazard: Fight in the Breston Plant Nuclear Power facilities and compete across multiple floors in locker rooms, restrooms with showers, control rooms, and the nuclear waste storage room.