Originally posted by: Alder
Here's my noobie assumption:
Random Game Store has a Kiosk, makeshift SNES testing station, etc. They need a game to use so they grab one off the shelf and slap a "SAMPLE" sticker on it.
Or it could be more official, who knows?
I'm not too sure either, I think it could be something simple as a kiosk version of the game too. The more official to the retail it looks, it could be a retail version that's for display, the more proto-ish with eeprom-ish guts the innards look, then maybe it's a proto.
I can also go with what 3Gen said, usually a game could go out to magazine companies or strategy guide writers.