I've actually gone around on the issue of same model for an item or different several times and come to the conclusion that I'm not sure....

My natural instinct is to get good quality and multiples of the same model so I can canabalize one for parts if necessary, the flip side is of course that if there is some inherent design fault I'm really SOL. I guess I'm confident of my capability to weed out the design issues so I tend to lean towards the commonality when I duplicate items.

I tend to have duplicates of some key items since I keep seperate kits in each vehicle, and a BOB in the house--all of which could be stand-alone if necessary.