Earlier versions of the Game Genies always have the Dash there, the newer versions have the dashes added to the line of code after you enter it. If I know my Game Genie history Nintendo didn't like the Game Genie and had put checksums in their games, I dont know if this is just for NES or not but, it seems likely they did something similar to SNES games too. this info came from Wiki I would assume it applies to third party titles too.
Around the time of the lawsuit with Galoob, Nintendo used other methods in attempts to thwart the Game Genie, using ROM checksums in later titles intended to detect cheat modifications. These measures were partially successful but some could be bypassed with additional codes. Later versions of the Game Genie had the ability to hide Genie modifications from checksum routines