A Texas woman delivered two sets of identical twins on Monay, a rare circumstance that happens only once in every 11 million births. The baby boys, Jacob, Jacoby, Jason and Justin, were the result of an invitro fertilization in which both implanted eggs split to form monozygotic twins. They babies were born at 30 weeks gestation, and ranged in weight from 2.5 to 3.4 pounds.