I have a vendor which sells copies of an object in its inventories, which I imagine is how most vendors work

However, for reasons best known to itself, and after this exact vendor has been working perfectly at its location for some weeks, it appears to have decided on a whim to sell the original instead of the copy, and now no longer contains the inventory it's supposed to contain, of course.
I know this, because the copy is renamed on rez, and when I tracked to the last customer who paid me, they do indeed have one named as the original, not the copy.
Maybe I should just put a dozen backups in there and run a check to see if one exists, and if not use another, since LL seem incapable of fixing perms?