A friend told me that you can only carry one at a time. The other must be in the truck with the lock on. In the past there has been a conservation officer on this forum answering questions. Perhaps there still is!
Pretty sure that in a blind or pit while hunting ducks and geese only one shotgun is allowed, You can have another in the blind but it must be cased and locked. Prevents someone getting around the max shells shot by emptying one gun and then picking up the other to continue shooting. Might not be allowed for the same reason. I don't think carrying a 22 for grouse or rabbits counts.