Used fetal Doppler need advice!

So I used my sisters fetal Doppler and got some interesting results. On my left side I found a heartbeat which read at 110 bpm. I was so excited! Then I checked my right side and heard a heartbeat that read 90 bpm! My own resting heartbeat is around 45-50 so I know it wasn't me! Any idea what to make of these readings?! My first US appt is on Monday and I'll be 8 weeks tomorrow. Just curious if anyone had results like this before and what was the outcome? Thanks!