I've heard of a few one shot, double kills, but the ones I've heard of were suposedly by accident! (not seeing the deer behind the intended target)
It's not a shot that anyone should intentionally try. Unless they are both perfectly aligned, you have too much chance of wounding the second one, and even with perfect alignment, there still a good chance of bullet deflection!
I probably could have killed three does with one shot this year, but I waited for the others to clear out of the way! In my book this is the ONLY ethical thing to do!