According to USgamer the 2DS isn’t at all what it seems. Instead of being home to two separate displays, the new cake-like slate console from Nintendo actually harbours one solid screen which displays two separate images. Nintendo have apparently opted for a singular screen to cut costs because it’s easier to “masks out the extraneous portions” with the casing than add in two separate screens.
What this means for the 2DS is that the top screen is essentially a touchscreen too but due to the harder plastic being placed over the top and the lack of software recognising the top screen as an input device it wouldn’t be much use. Theoretically however, this potentially opens the 2DS up to hackers which could turn the 2DS into the first dual touchscreen console from Nintendo.