Can baby switch sides?

Ch

When I had my first ultrasound at 8w1d the baby was on the left side of my uterus, we heard the heartbeat and all.

Today at 11w5d they used a doppler to hear the heartbeat (no ultrasound) and they found the heartbeat on the right side/ almost in the middle of my uterus...

Can the baby move just like that? Or can it be twins, and the ultrasound tech just missed it?

8w1d ultrasound. ^