The Nintendo 3DS is not multi-touch. That hasn't stopped Namco Bandai from making a game that requires two touch pens.
So players not only have to hold two touch pens like total goobers, they cannot use them at the exact same time. Well, they can, but the multitouch won't register. Only one of the brain training-type games shown do seem to require the akimbo pens due to the location and the speed at which flashing blocks appear on the screen.
But for the rest of it, are two pens really necessary?