This comes up as Big Mutha Truckers, but I can't find out what it actually is. SLUS-20605 is the catalog I see associated with it. The only results I find for 20291 are ISO results. I can't find any edition information, like maybe it was a NFR version or something, but I find nothing.
SLUS-20291 Is the internal serial number from the disc while SLUS-20605 is the serial printed on the disc surface.
So there is a possibility that there is another release of the game too.
ATV Offroad Fury 2 had a Not For Retail version that had a different catalog number - it was bundled with a Network Adaptor so you could play online. I wonder what the other version for Big Mutha Truckers could be. Or maybe there isn't one and something weird just happened with the numbers. I don't really know how it works. It seems they have to register the number when they start making the game, not when it's released, because the numbers certainly don't follow chronological order. Maybe something weird happened with SLUS-20291 and so they used SLUS-20605, but the file was still titled SLUS-20291.
But then I really don't know how it works