At home fetal dopplers for twins--do they work?

Kelly • I'm 29 years old living with my hubby in the suburbs of Chicago. We're so excited to add another to our little family!
Hi ladies! At my upcoming doc appointment I am transferring offices, so since this is my first apt at the new office they won't be doing an ultrasound, just taking my history (I'm so disappointed!). I'm 13 weeks though and anxious to hear my the at home dopplers work? Are they worth the money? I wasn't sure if carrying multiples affected the results (ie harder to hear the two separate heartbeats or something along those lines). Do any of you use one?