Well, actually, if you are talking about getting at least 360 one way, and then another 360 the other way in the same jump...
It IS physically possible, IF you are also flipping, by using "tilt twist" (which is the easy way of saying - conservation of angular momentum). Tilt twist is basically converting flipping momentum into spinning momentum and that twisting can be stopped and reset in another direction if an athlete has the airtime to do it.
It's kind of complicated and doubtful anyone on here would really get it or care, but, for example, by using tilt twist, a freestyle aerialist could perform a full-tuck-full with the full twists in different directions.
Anyways, ask a gymnast or freestyle aerialist, they could explain it to you.
I think some of them have done it at water ramps, but don't know of anyone who has intentionally done it on snow.