Is this a twin????

During my ultrasound this morning I saw what looked like a second sac and baby, but I didn’t notice until my husband and I watched the video back together at home. The doctor quickly glanced over this screenshot and focused on our baby for the rest of the exam, but I can’t help but wonder if this is a second one! Can y’all please tell me if I’m being crazy and this is some other thing than a baby?! My appointment was so fast, I’ll make sure to ask to double check next time!

Ours is the one on the left !