Can Doppler detect twins?

Megan
11 weeks and have my first Doppler heartbeat appointment in 2 days and won't get an ultrasound until after 20 weeks. Can a Doppler at the birth center detect twins? I'm nervous that if I did happen to be carrying twins it would be crazy to not know until half way. Do they still test hgc at 11 weeks? I've never gotten a hgc blood test.