There's nothing wrong or unbelievable about having a name that someone else already has. It's just like when you find a person on the street who has the same name as you. It's certainly not a strange thing.
I had more but I'm a little fuzzy right now...
Definitely try some communication with her, though. Consistent reassurance that she will be believed and accepted, and that you guys don't care if her name's the same as someone else's. And that if she doesn't want to say her name, that's ok, you still want to get to know her.
-- Wed Sep 05, 2012 11:43 am --
As for the letting them know you can hear them thing... sometimes you just have to wait it out and it can be hard.

But never stop trying to communicate with them or trying to find them. Just because they can't hear you right now, doesn't mean they never hear you.
Maybe try singing back to Jacob? He might only be able to hear in song or something as a reply. It might be his way of communicating right now.
As for the girl, just keep trying to communicate with her, too. And try to help yourself feel as comfortable, relaxed, and calm when you do so. When you feel better, it'll help her to feel better. Let her know that she doesn't have to share her name if she wants to come forward and stuff, too.