I don't have any Dreamcast games, but I can tell you that in Canada, particularly back in the 6th console generation and a little earlier (mostly with disc-based games in my experience) this is common. I've bought plenty of PS2, PSP, and some GameCube games with the English/French manuals stuck to the back of the sealed game. That being said, not every sealed game I've ever bought from back then has done this (and I've lived in Canada my whole life).
To directly answer your questions:
1. Yes
2. Probably, but I don't know about Dreamcast games specifically.