Adding 2nd baked sound to an f-curve and 2nd Driver

I should have posted this in support animations and rigging. So I will repost there.

Administrator: Please close this post.

I have baked a sound to an f-curve on an empty, then made a driver for a jaw bone. Works well.
How can I then bake a new sound to the empty and create a driver for the same bone? When I try to create the second driver (same x axis), there is no place to add the driver; and you cannot add to the keying set.
Blender 278c
Thanks for your attention.