Using both the hot shoe and the PC outlet

Lets say I want to fire two lights; one is a studio strobe (AB800) connected with a PC cord to the outlet on a 20D, the second light is a hot shoe flash on the camera. (Key & fill respectively)

I'm pretty sure that both will fire but would the trigger voltages be cumulative? and possibly too much for the camera?

I realize that if I don't plug the cord into the AB800, it will be triggered optically, which is fine for most situations...but I'm envisioning a scenario where I'm shooting formals at a wedding and guests are around and wanting to shoot with their cameras...which would trigger the AB800. With both lights physically connected to the camera, other people's flashes wouldn't interrupt my shooting...except to bother the subjects

The 20D manual specifically states that both PC socket and hotshoe can be used at the same time.

The trigger voltage of the AlienBees is under 6 volts, and presumably so is your hotshoe flash (you didn't mention the model).

You'll be fine.

Thanks Curtis. I should have known...RTFM