I believe the OP is referring to an actual library, like the one you check out books from. I've been able to check out Wii games from a library before. Since the save data for 3DS games is saved on the cartridge, not the 3DS itself, if he were to get a different copy of Omega Ruby, it wouldn't have the save data of the one he got from the library, so he wants to know if he could transfer the save data from the library copy to the other copy. Since he'll return the library copy at some point, he'd lose access to his save file, and he doesn't want to start over. At least that's what I'm getting from all this.