I just found out something interesting from another forum, if you hit two places at the same time on single touch screen, it will register the press halfway in between the two. Which means that you could register a button and a direction pressed on screen at the same time by having an invisible touch point in the screen area in the correct spot(if the controls are on either side, like the iPhone NES emulator) to register both.

The effect isn't 100% prefect, but works most of the time, and you can shift from a single point press to dual. Problems include; only registering one press about 10% of the time, sometimes you have to lift up completely for it register both,and on a rare occasion it thinks you dragged the pen to one point to the other.

If you want to play with effect, open up Sketch and draw a gamepad, and try pressing a direction and a button at the same time, you'll usually get a dot in halfway between the two places you pressed.