Twins or Nah?

Calla
So we went for our first ultrasound Friday. The ultrasound tech took lots of pics and did more than one measurement during the ultrasound; but I thought it was normal procedure. When my husband and I went in to do our follow up with the midwife, she informed us that there appeared to be 2 fetuses. Now when you use the word appears, I'm thinking it means it's a possibility. But then she gave measurements, said there was a second heartbeat and a second fetal pole and that they are in the same Sac. However, we were scheduled for another ultrasound in 2 weeks because I was only 6 weeks and 1 day, and they want to be certain. When I got the appointment sheet, where it said  number of fetuses, there was a 2 beside it. Anyone else experience this? If so or if not, what are your thoughts?