Jon writes:
So... two oral cavities? Two tongues? Four sets of teeth?
We could speak out of any convenient orifice. [Insert joke here.]
If the lips, teeth and tongue were significantly different from the ones we use for eating, our languages would have evolved in different ways (or would have been designed in different ways). All we really need for speech is an air supply and some sort of modulation apparatus.
And we could talk with one mouth full without being rude.