It's stuff that 8ig8 doesn't know is already on hand. Keeping certain track of it takes more time than the repurchase is worth, for occasional use. A related situation is why lots of people have several identical pairs of scissors, can openers, and other things that they don't use every day: eventually, as you buy more of them, the time it takes to find one costs less than buying a new one. But 8ig8 has this problem with things that are hidden in the attic; just figuring out whether it is in there at all is painful.
Ironically, this is exacerbated right after you move, too: I have things which I know I own (diagonal cutters, magnetized screwdrivers, etc), but which I _cannot_ find anywhere. It's in some box somewhere in my garage, but not in my "tools" chest, so it's more time effective to buy a replacement.
