I don't know if this is a bug with the ROM or with the actual game, but if you tap kat and then don, sometimes the touch screen will register a hit in a different area of the screen even if you haven't touched it.
Refer to picture below. If you tap kat in that point and then don in that point(yellow circles), the screen will register one hit directly where they meet in the corner(purple circle). It's not a problem with my screen, I tried out this trick on Taiko DS 1 and 2 and this doesn't happen at all.
It happens only occasionally, and still not enough to mess up a perfect run, but it still annoys me.

Refer to picture below. If you tap kat in that point and then don in that point(yellow circles), the screen will register one hit directly where they meet in the corner(purple circle). It's not a problem with my screen, I tried out this trick on Taiko DS 1 and 2 and this doesn't happen at all.
It happens only occasionally, and still not enough to mess up a perfect run, but it still annoys me.