In that case, scrollto behavior is not what you are looking for. ScrollTo is for camera.
What you want to use is probably Bullet behavior, and then use events to limit the players to their areas.
One possible way (not the best way but an easy one) is:
if player1.x > LayoutWidth / 2
player1.x = LayoutWidth / 2
if player2.x < LayoutWidth / 2
player2.x = LayoutWidth / 2
This will make player 1 not able to move to the right half of the screen and make player 2 not able to move to the left half of the screen.