Were they both from the same hatch? Don swears it's an incubation problem, which would go along with the observation about assisted hatches. If you know which cock & hen they came from, and still have them paired up, I'd keep a close watch and see if you get any more. If you don't, I'd suspect something went wrong during incubation. If they keep popping up, then it might be the parents. I usually see 1 or 2 a year, usually in the buffs but occasionally in lavender, too. Knock on wood, so far none this year.