So, the one who declined the challenge, possibly because he would lose, still remains undefeated. The challenge was accepted, but they could not agree on the rules. The match was stopped by the Police - one side could have chickened out and doped in the Police. Then both fighters are correct to claim they were undefeated. Ask for specifics - year, occasion, city, tournament.
Vagueness is a tell-tale sign.
Some masters travel around the whole of Philippines, relentlessly challenging any fighters they hear of. There were a few masters who were supposed to have travelled the length and breath of the whole of Philippines, mercilessly and relentlessly seeking out just any fighter and issuing challenges. Surely they would have heard of each other and have crossed each other's paths many times. And if they did, at least one of them would have come off second best - in other words, defeated. We already know some famous and well known Arnis families like the Illustisimos, Saavedras, Canettes, Romos, and some other famous individuals like Jose Cabalero, Jesus Abella.