I think Sonic 3 used that for the level select, too.
EDIT
Okay, that's UpUpDownDownUpUpUPUp. Close enough.
You're not completely wrong buddy. The US version of SONIC1 used an code which was slightly similar to the Konami code. Odd enough the Japanese SONIC1 uses a code which is closer to that one you use on SONIC3. (And the same cartridge would behave differently if you were playing it on a SEGA GENESIS or an MEGA Drive console, btw.)