1943 is a simultaneous 2 player game.
A good example of a alternating games are: pacman, ms.pacman, donkey kong, Time Pilot and many many more. You can;t use joysticvk #2 to play when it's two players turn (unless your cab is a COCKTAIL table).
There are some games that are alternating and can use the second player. You need to setup (F2/CONFIG/DIP-SWITCH) each game for that (if it supports it).