If there was no evidence it wouldn't be reported on, especially if even City is implicated. In fact, as
@Gungerz pointed out there is evidence of two players using different names.
EDIT: Moreover, the article states not only are both clubs aware of the evidence. But that even other parents of fellow youth players were aware of something and reported it to safeguarding, which was never acted upon. The only reason it hasn't been made fully available is because we are potentially dealing with players who are still minors.