What happens if both players have 8 points at the same time?

In Riftbound, it is not possible for both players to reach 8 points at the same time.

According to Rule 463.6 (for 1v1 matches), the game ends the moment a player reaches the Victory Score:

"The first player to reach the Victory Score in Points wins the game."

Because the game ends immediately upon a player reaching 8 points, the second player never has the opportunity to reach that same total. Even if a game action (such as a triggered ability or a showdown) would theoretically result in both players gaining points, the game state is checked continuously. The player who reaches the Victory Score first wins the game, and the game concludes before any further points can be awarded to the opponent.