This fighting game match up is based on similarity of aspects of the game play, essentially the one-on-one matches, martial arts elements and the range of fighting mechanisms that can be deployed (punches, kicks, etc). In addition, both of these games started as arcade favorites. While Double Dragon started as a single player game, it eventually adopted the co-player mode, although different from Mortal Combat, the two players are playing together rather than against each other. And, of course, Mortal Combat is well known for the finish… using several key patterns you are able to completely demolish your opponent (they didn’t need that spine anyway).
Are you a go it alone kind of player, or would you like a little support to defeat your enemies? Your call.
Double Dragon: http://en.wikipedia.org/wiki/Double_dragon
Mortal Kombat: http://en.wikipedia.org/wiki/Mortal_combat