My wife has tried DP numerous times and says it isn’t like the porn films. Most of the time it’s uncomfortable, they constantly slip out, impossible to get a rhythm going and one or the other usually cums within a few strokes. She did have an older black bull that would have her lie back on him. He would penetrate her anus fully, but not attempt to move. The other guy would then fuck her cunt. When my wife orgasmed her ass would tighten and spasm, causing her bull to erupt in her ass, this would usually set the the other guy off as well. He was the only guy she really enjoyed dP with.
I have tried it with her, with her on top of me and me in her cunt. As the other guy entered her ass, I could feel his cock rubbing against mine, which caused me to ejaculate. He hadn’t even got all the way in, my cock slipped out of her, but he carried on fucking her until he came.