Question about fetal Doppler

So I’m not sure if this is something to mention to my doctor or not but I have a at home Doppler I’m 14 weeks and I’ve noticed for a couple days now I’m picking up 2 heartbeats on my Doppler. So I did some research and found I’m probably picking up mine or the placenta. Well the problem I have is my babies heartbeat is about 147 well the second heartbeat is 156??? I know that can’t be mine does the placenta have that high of one?? I went back and forth between the 2 just to make sure they are consistent and they are. Now I’m freaking out thinking there are 2 babies in there! I know it’s a long shot that the doc might have missed a twin but from what I’ve read it’s not completely uncommon. Has anyone else experienced this?