Recent EU guidance (issued in June 2016) which is admittedly non-binding, suggests that it is per passenger.

In order to preserve this, each passenger will need to make a separate claim and reference the fact that a claim is being made against the same property by the other passenger (so as to avoid AF asserting fraud and denying both claims).

Beware of trying to "use another's allowance" because that is not what the Montreal Convention provides and becomes the easy way for AF to deny the claim.