Yup, double entry is possible. And it feels very good, too. For the top and I guess for a good, experienced bttm, too.
This does not happen every day, so I guess, experience is a limited factor here.
The physics of it is somewhat compliacated.
Two Big Tops are fine, if the bttm dude knows how to relax and if he is well, experienced.
One Big and one Small top work fine, too. The Big one usually letting the bttm dude impale himself on it and the smaller top taking the bttm atop the bigger dude.
Lots and lots of lube are needed, a bit of patience, and a very cool, of somewhat persistant attitude. (Don't get dispirited too soon. No one said this was always easy.)
Take care, go safe and enjoy it.
KD
