This master's student in USA even claimed that this master was the leader of the Doce Pares at one time. This claim has been effectively rebutted by the Doce Pares. Masters do not do that sort of thing, they don't need to, and they have other better things to do. Until recently, many masters engaged in 'death matches' . Masters do not go around looking for death matches to participate in.
Death matches are rare.
First of all, most challenges to fighters stipulate terms for victory and defeat. Death is seldom stipulated. Secondly, killing is killing and is punishable as a crime. Whatever the reason or dispute is, killing someone is a criminal offense. The winner has to go to jail.