Possible twins!? 😮

I had my first ob appt yesterday. This is my rainbow baby after miscarriage in June. To my surprise the dr is thinking im possibly carrying twins!! It wasn't clear on the ultrasound but there is something else in there besides baby #1! Could possibly be blood but it wasn't a solid black like fluid would be. At one angle it looked like we could see the circular yolk sac in gestational sac #2! Such a surprise and now waiting a week to know for sure has me in such suspense!! Any similar possible twin stories!?