Twin heart beats?!

So I have this app on my phone, that uses my sound recording device to record babies heart beats. Now, I was skeptical at first, but now I get a heart beat every time I try. Except to me, it sounds like a continuos beating, not the normal swishing of one heart. But kinda like 2 hearts beating in Tandum.  I'm only 9 weeks and have yet to see my dr for ultrasound and such, but what did yalls baby heart beats sound like at first? Am I going crazy? Could there be twins in there?!