How do you breed two headed in dragon city?

You can breed a two-headed dragon by breeding a pure dark dragon. A pure dark dragon happens to have two heads. You can breed one by breeding a pure dragon with a dark dragon (though not allbreedingwill produce a pure dark dragon). You can get a pure dragon by breeding two legendary type dragons. Everything else is up to you.

There is also a dragon called the "Two-headed Dragon". However, you can not breed the 'Two headed dragon' in Dragon City. This was a special dragon that could only be obtained in mid-October of 2012. During the dates it was available you had to earn 10 points in the carnival games. But that is OK because the pure dark dragon is more powerful anyhow.