Exactly. "Sublimits."
Do you mind sharing the name of your insurance company? One of the things I'm sussing right now is what companies are willing to do such a rider.
Bumping an oldie but goodie regarding this perennially nettlesome issue in insurance matters regarding valuation. Perhaps you've since made the move to a smaller house.
Whether it be what you originally paid or what it would cost to replace the disc, valuation is likely going be negatively...