Early twin ultrasound

Amy • Mom to 4 beautiful girls. 3/3/10, 4/27/14, 4/8/17, 3/7/19.

How is it possible for both babies not to show up in view at the same time? As in mo/mo or mo/di twin pregnancies. Does anyone have an pictures of early ultrasounds that didn’t capture both in one picture or simply an early ultrasound of mo/mo or mo/di twins?