The doctor twins
My committee sister Jill (we have the same doctoral advisor, and additionally we share another committee member as well) and I have been expected for some time now to finish our degrees at about the same time. Sometimes it looked like Jill would get her research finished before I did; other times it looked like I was pulling ahead, but it was clear that we were roughly on the same schedule.
We were negotiating dissertation defense schedules with our committees at about the same time, too. After past experience with trying to coordinate schedules among multiple people, I was pleasantly surprised how easily I proposed 10 AM 27 July 2006, and everyone instantly agreed to it.
Jill's scheduling wasn't quite so easy, as she had to coordinate with a committee member based in DC. It turns out that the only day he was available in Seattle was--you guessed it!--July 27. So she had to take 2 PM on that day, although she was very apologetic about scheduling it on "my day". I didn't mind, though, and I suspect our advisor was very pleased at the efficiency of graduating two of her students on the same day, and--as it turns out--even in the same room, when my larger room got pre-empted by a workshop.
So the ongoing question of whether Raven or Jill would graduate first finally came down to "Raven", but as it was only 4 hours, I consider that the same for all practical purposes. If we were committee sisters before, I think this makes us doctor twins now.