Yes, I'm familiar with the Tuvan throat singers. It takes years of practice for them to do what they do. Note that I said the ability to hit more than one note at a time usually indicates there is something very wrong with the vocal chords.
Somehow, I doubt David Lee Roth is a Tuvan throat singer (or any other variety of Overtone singer). I suspect the reason he's able to hit more than one note at a time is because he's screwed his voice. Come to think of it, after hearing what he does to his throat to hit the high notes, I'm certain that's how he's able to do it.
"People generally quarrel because they cannot argue." - G. K. Chesterton