Twins?

I went for my first ultrasound at 7 weeks and the ultrasound tech noticed two “things” in the same sac during an transvaginal ultrasound. She tried various angles and such and I even got up walked around then when she tried again it wasn’t visible anymore and of course his was when the doctor came in. The tech was confident that it may be twins in her 20+ years in her profession, however she believes the baby we were able to see the heartbeat was in front of possibly hiding it. Has this happened to anyone? If so were you ever miscarrying one of the babies and your body absorbed it? This was also mentioned by my OB that could possibly be happening and I’m not sure if it was just so I didn’t “get excited” or True since I am not bleeding or have any cramping. What else could it be?! I go back in two weeks so will know for sure but just curious is anyone else has experienced to his type of situation? Thank you in advance!