Just to be clear, this is not allowed. But, it is your responsibility to check before the match starts. Once you start the match, you basically agree to play with whatever player your opponent is using.
No i told him it was not allowed so we started over. But then he asked where it was written and he was right i just assumed it was not allowed and i couldn't actually see it somewhere written in FAQ or rules.
Maybe put more clear in FAQ for new players that join the tour and are not aware?