Multiple backups do provide peace of mind and security, but add weight , critical when traveling one foot. I multiple up in two categories - fire lighting - matches in waterproof case, Bic lighter, and ferro rod of some sort and light - usually three sources- my key chain light, a really good headlamp, and one additional light (varies with circumstances). This follows the traditional caver principle of three independent light sources which is a proven prudent measure when underground in a cave.

For everything else, I tend to favor adaptable, versatile gear that can serve a variety of uses. I can get along just fine with one knife or multi-tool, although sometimes a second blade will sneak in when I don't need to worry about weight.