That's why I haven't done it yet. Sarah Lee wasn't in the picture at the time. I might have been able to calm my neighbor with one pen, but two....
They can be adjacent and share a common panel, but they can't be crowded together like that. 'fraid somebody would get kicked.
One 12X12 really isn't big enough for two horses - they could get hurt unintentionally. I don't even like my mommas and babies left in a 12X12 very long.