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---