Actually if you have multiple users with the same email an email should be send to each user to reset there password.
Now as far as the messaging error. You can turn that off but I am more interested to know if all your files are indeed new as previously posted. essentially I can see your allowing both email and messaging to be used. We send in the send_ppemail function a 5th parameter called $sendid which is a users userid really.
I am just stumped on why yours would be empty which causes your error.
Code:
Content visible to verified customers only.