There has to be an explanation ...

So yesterday I received my fetal Doppler in the mail and as my husband was listening to the baby’s heartbeat (it was on the very far left side of my pelvic area) playing around, he put the Doppler in the middle of my lower stomach (panty line area) and heard nothing. But then he put it on the very far right side of my pelvic area and heard another heartbeat??? When I was 11 Weeks my doctor listened to the heartbeat for a few seconds and that was it- didn’t hear anything else. I’m 13+3 now and that happened and i just need to know there has to be an explanation. This all happened within a couple seconds and I’m honestly scared lol