Just hatched twins!!!!

Okay, April fool's day is over. This can't be! I set 12 eggs on 03/11. One didn't develop. Two were quitters. This morning we started hatching. I gave one of my broodies two of the eggs last week - she now has hatched two babies. Shells were accounted for, marked as this 3/11 batch, and I only gave her the two. I had five hatch today and pulled them plus their shells out of the incubator to give the others room to hatch, so that's five in the brooder. I'm always careful to pull the shells out so they don't end up around another egg and block the baby from hatching.

1+2+2+5=10. However I count it, that's 3 bad eggs, 7 babies, and 2 eggs still to hatch in the incubator. I just opened the incubator to pull out the babies and there were THREE BABIES and only TWO SHELLS! I'm the only one here. No one could possibly be playing a prank on me. I never noticed anything unusual when candling, although one of the eggs was large, but that hen always lays large eggs.

The only thing I can figure is I hatched twins! Is this possible?