For some reason, I feel compelled to clarify my response. By "One at a time," I meant one in me at a time. I actually prefer when they take turns sharing me going back and forth. It's exciting not knowing what's going to happen next - Are they getting ready to switch? Will he want to flip me over or stay the way I am? Does he want me to get on top? Which one will cum in me first? Is it going to be this time? After the first guy cums, the second is quick to follow.
We've had variations on this where they would be in and out of my bum, or switching off but with one guy going in my pussy and one in my bum, or after the first guy cums he switches doing oral on me until he's hard again. I've also done this with three, and once four men, but there were other women there too, we were just swapping quickly for fun and all of the cum wasn't put in me. (Makes me sound like a real swinger, but I've only been with five guys in my life; and yeah, and more women than that.)
DPs can be nice, but the positions are not that comfortable or conducive to good fucking.