There is something of that nature for hunting migratory birds. As the shotgun is supposed to be limited to the number of rounds, I guess they don't want you sitting there with 5 shotguns ready to rip and not have to reload
As far as hunting with two rifles, I combed the regs as well as the wildlife act with regard to that and could not find anything. I do not believe there is an issue at all.
Carrying a rifle during bow season, definitely no law specifically against that. There are animals open to rifle and animals open to bow, so legal opportunity for both. That aside (even if there was nothing open for rifle) there is still no specific law against it. A conservation officer would have to believe you were using the rifle to shoot species that are no open for rifle and there would need to be evidence of that for a case. Being charged for simply carrying the rifle during bow season would be a "thought crime" ... very unreasonable and I have never heard of it happened so I have zero concern about having a rifle around during bow season (in my case for protection)
That said, if anyone is concerned about it, the best thing to do is email the ministry for clarification as they are the authority on the matter. They will reply back with clarification on the issue and then you can print out the letter, carry it around in your pack or whatever. In the event you run into an issue in the field you can present said letter to clear things up.