It actually isn't, the map is. Map content from each of the two dlcs was added to the disc so you wouldn't have to download a 20GB+ file for both of the dlcs, as if they did not add it with the disc you would have download the entirety of the Mars, Venus, Earth, reef and Moon maps all over again, both times. And tbh, why the -blam!- does it matter when they add it to the game anyway, if you bought it you'll get it anyway, if you didn't you won't get access to it. Having dlc ready months before release is an extremely common thing in game development, it takes years to make a game like destiny. Make of that what you will.