I also don't get it why your scores show up multiple times. It should only show the best for each player (name changes don't matter, it uses random generated unique id). 🤔
Never mind, it looks like indeed did take names to account too which I changed now to how it should have been. I'm pretty sure it was like that earlier, I've been using this same leaderboards on all my games and it used to behave so that even changing the name afterwards and doing a "bad run" would update your name for existing top scores.