I've seen the rom side differ on several PCBs. It's the reason I'm interested in the reverse side too.
From my research there are at least 5 different versions of this game - 2 JPN versions, US version, World version and Koren version.
I've also seen a Korean PCB with the English License seal.
Trying to figure out what's what- call me weird, but I've developed an obsession with this game and different versions over the last year.