Mary and Frank just received news that they are expecting their first child and are over the moon. When Mary is 8 weeks along, they attend their first doctor's appointment where an ultrasound is performed to confirm the pregnancy and to their surprise they see not one but two babies! The doctor confirms that he observed two individual placentas and two individual amniotic sacs and thus tell the happy couple that they are expecting dizygotic (fraternal) twins. However, during an ultrasound at a later appointment, Mary and Frank find that they look very similar and suspect that they may be identical twins rather than fraternal twins. Is it possible for the babies to be identical twins even though two separate placentas and amniotic sacs were observed?