In fact the non working servo doesn't even hold, its like theirs no signal going to it at all.
Then maybe that servo isn't getting power?. It will hold without a signal I think. Anyway either its a wiring problem or you've burnt-out pin 10. Easy to test either hypothesis with multimeter.
I went ahead and put a scope on pin 10, and I'm not seeing anything on it. Thinking that I might have a burned out pin like you said, I set it up to digital out, and had it pulse every second or so. It seemed to work fine, I could see the changing state on the scope.
I then plugged both servo's onto the same pin, and both servo's run fine in parallel, so it doesn't look like a wiring problem. Again, it seems like only pin 9 is able to send out pulse width. I think I have a netduino around here somewhere, I 'll grab that and test it, and see if I can get them moving on separate pins with it. If it works, I think that pretty much eliminates the wiring as a cause.