Sometimes when I buy something and it's not right, that's it, only buy the one and it gets reboxed and stuffed in a drawer. Things I like and want to have available I'll buy multiples (two, three, more), but they aren't necessarily spares, they're just in different kits.

Yeah, this is an expensive thing to do... I am one of those people.

I have 3 pair of the same shoe in different colors.

I also have the same things in my bug-out-bag as I do in my camping, or vehicle kits. Eventually a BOB won't be necessary as I duplicate the gear all over!! LOL

I have learned to buy one test, and then by more... too many times I have ordered multiple from the get-go and learned later it was wrong and ended up with multiples.

tools..buy 2 and beat and abuse one then buy the 3rd.If it pass's the Test.

The expensive thing? Nope, it's the frugal thing to do.

When I find something promising on sale, I may buy one to test it. If time presses, I'll buy three. Or five, provided I can return the unopened ones. Guess I have a good eye, because most are keepers.

(We have a generous cash fund that's dedicated to grabbing deals when they come along. Unlike the poor suckers who buy the latest TV-buzz-whatsit on credit-card credit. Oy.)

If I can't use them all, they go into the Gift Box, providing high quality gifts to people who will appreciate them. (We cultivate contact with these kinds of people, so it all works out.)

I take care of my gear. It lasts. And by the time I need a replacement, I can guarantee the original will be out of production. So if it really fits, or really works, I buy spares. Boots, knives, multitools. And boots are the toughest to find worthy replacements for.

Call it my hedge against inflation, or planned obsolescence, or the flavour of the month.

i buy two,not for the reason's you mentioned but to have a spare around if the first is lost,used up or busted.example,i bought two PAL LED lights because they are just right for my camping needs.one go's along and the other is still boxed up and put away.
skin glue,got two because of the price and when i use up the first,if ever,i can replace it without waiting.a last example is a camping stove that i found to be another "just right". the Borde pocket stove is very hard to find.one fellow in Germany got the rights when the company folded many years ago.the old ones are found on Ebay for around $100 i got two.one for canoe trips and the other still NIB.if the first lasts for all my camping years i could sell the other to pay for a knee replacement in 20 years---

The first model is OK but has it weaknesses.
The second model usually corrects those.
The third model is usually rubbish.

I usually buy one to use. If it's good I buy a second.
But it's for damn certain that I won't buy a third.

i already own to many things and second and third item is just taking to much space and money.

This brings up the issue of technological obsolescence. There must be a dozen stoves on the market which are lighter, hotter, and cheaper than the Borde which was a hot stove (what else?) in its day. Don't get me wrong, I carried a Borde and it proved crucial in a really rough unplanned bivouac in the snow many years ago - it is probably the reason I have all my fingers and toes today. If it works for your situation, great. I don't mean to dis your choice of stoves.

The Borde went off the market because it tended to morph into a bottle rocket if overheated. Mine died when the fill plug blew out. I replaced it with a Primus which served for many years and is now a souvenir above my desk - it still works, if needed. Nowadays I use either alcohol or a Pocket Rocket.

$100 on Ebay? I think I paid less than $10 for mine (1962). As a starving student, I watched pennies.

Does this apply to wives too?

Hikermor..the Borde is not a bit of survival gear but just something i take on canoe trips for "fun".it falls in the same category as a old shortwave radio i fool around with at nite,a Hallicrafters S38,i could buy a modern one with digital tuning.
my real canoeing stove is a Peak Feather that i have used for many-many years and has never failed.Hikermor,your the first person that i have heard of who really had a "Borde Bomb".i thought it was the shape and pre-heat that gave it that bomb nick name.