Actually twins do get missed. Not saying that it happens all the time. It's rare but it does happen. And I'm also not saying that "a bunch of random people" know more than the tech. But that it's possible that the tech missed it because she was more focused on trying to see the heart, face and gender. She had a hard time seeing those things because I have a frontal placenta and the baby was facing the placenta. And the face that people are seeing is between the baby and the placenta, which makes me wonder if there is one hidden in the placenta.