Two on one yolk would have not made it to peeping due to lack of nutrition. Two yolks have been known to make it to the end, but often not alive. Since an egg is the perfect closed model system nutrient wise, if one died, there is no "mother" to adsorb the dead tissue/cells. Pics are a must! And leave it in the bator till at least day 22 to ensure yolk absorption. Opening the bator now is a big no no as it can compromise the hatch!