Brian, Only need one.....
Honestly though, I have never been a "back-up" type of guy.
For 6 years in the Marines,I carried an M-16.I took care of my rifle,it took care of me.If we ran out of ammo and got over run,I grabbed it by the barrel and it became a club.
As a part time Deputy Sheriff,I carried a .357 mag. I only carried my side arm no "back-up" gun.
When I hunted the "Big Woods" in Maine and the Adirondacks,I only carried my rifle. One year I decided to carry my .44 also. I had 3 pounds of dead weight on my hip for a week. After that the only time I carried it was if it was the ONLY gun I was carrying.
I only bring one bow on a hunting trip.....the one I'm going to hunt with