[Unakjyfk]

I'm usually fairly knowledgeable when it comes to the rules of the game, but I had an incident that came up during our round this afternoon that I had no clue how to answer. The guy I was playing with was playing a Titleist Pro V1 number 2 with a logo of a company I had never heard of. I know you are supposed to have some kind of distinguishable marking on your ball and he was using the logo as that marking. He hit his second shot on a hole just left of the green and it ran down the hill just past the hazard line. It was still very much playable. When we located his ball, it was sitting right next to another Titleist Pro V1 number 2 ball with the same logo. We had no idea which ball was his. Both balls were sitting just past the hazard line, but both were playable and had very similar lies. What is the ruling for that situation?