That is a thing, as VM do ask for equipment to be returned when the customer leaves or upgrades to a newer model, with the older one later on being issued on to another customer. Someone at VM probably forgot to factory reset the STB, so as a result the old recordings weren't erased before it was put back out for use.
What kind of problems are you having with it? That information will be helpful for those who know more about the TV side of things.
Edit: Late typo fix 