Yes, that's correct. In PICO-8 each player only has access to 4 directional buttons and 2 other buttons. Thus, to have enough buttons to support dual-stick controls, the game actually uses two players' directional controls at once. In the HTML5 version I can manually map both players' controls to one controller in javascript, but in the native version of PICO-8, joysticks will only ever map to one player's controls at time.