Well, besides who their boyfriends are and the fact that DB has experience in actually training wrestlers in APW, Inoki Dojo, and Ring of Honor, Nikki was laid up for a while and expected not to be able wrestle ever again.
Yeah, not so weird when you think about it. Though since they started dressing differently (and Nikki bought some boobs), perhaps some of that is to emphasize that they aren't so twinly any more?
...Nah, giving 'em too much credit.