I don't think that it makes a difference as to who owns the debt.
Point is, your "friend" didn't pay his bill. It really doesn't matter who is trying to collect the debt; it could be a possible agreement between the two companies, but you don't know that do you?
so what happens? Your friends credit goes down the tubes because of failure to pay on debts owed. Do you think it will be reflected on Chase, WAMU, Providian, or your "friend"?