As the man said, there is no back to the US GoT unless there was a non-pack-in version. There very well might have been actually, I don't know. I too bought a US Duo, and yeah it just came with a stack of instruction books. I think they also sold the same 4-in-1 packed with the Super System Card in the US for TG-16+CD owners...didn't they? I can't remember. They probably got the same backless case though.
As for SFII', if you have the book and the HuCard then what you actually need is a back, and a front. The game came in a double case. I have the game, but I don't have a scanner. Sorry.