This indicates that perhaps Birdo was meant to appear as a playable character, but had to be left out due to space limitations on the DS cartridge. Since the Egg 2 is unused, its stats are unknown (most likely though, they would be similar of the same as the Egg 1). The name for the kart in the game's coding is called: kart_HH_b.nsbmd and kart_YS_b.nsbmd.