Sure. You might just need to adjust the volume settings, but here is one way you can test that both mics at least work:
Install pavucontrol and gnome-sound-recorder:
apt-get install pavucontrol gnome-sound-recorder
Open pavucontrol (by typing pavucontrol into a terminal and hitting enter, or tapping Show All Apps then tap PulseAudio Volume Control icon). On the window that comes up, switch to the Input Devices tab, take note of the port for Built-in Audio Headset Microphone (default is Handset Microphone, I think). Change it to Stereo Microphones, and tap the lock icon on the right side to allow setting both microphones independently. Take note of their default position and set them somewhere around 40-50%.
Now open up gnome-sound-recorder, make sure Audio Channel setting is set to Stereo, then hit record, and switch back to pavucontrol. Gently blow on the top mic (pinhole near the center) and watch the VU meter (blue bar just blow Front Right slider) and it should jump around quite a bit. Then gently blow on the lower mic (right hand side of USB port with screen facing you), and again watch the VU meter. Now you can switch back to gnome-sound-recorder and hit stop, save it, then plug in some headphones and play back the sound. The top microphone corresponds to the left audio channel, bottom to the right channel, so you should hear whooshing noise in one ear, then the other.
After this, don’t forget to put your settings back. I believe the port setting needs to be set back to Handset Microphone for calls to work properly (haven’t tested it though). There also seems to be some kind of mixing going on where it always listens to both microphones but the ratio of sliders determines the sensitivity of each, but even if you turn one all the way down, it still picks up audio from that mic. Not sure exactly how it works… again, I only just got mine working at all yesterday. I’d recommend starting out by turning up the right channel a little and the left down a little, or maybe both sliders up a bit and roughly equal in value, and experiment to find what works best for you.