A caliper that has seized on its slide pins will wear one pad to metal while the other still has material left.
Listings here are side-specific. Left and right calipers are not interchangeable because the bleed screw and the parking brake lever, where fitted, are mirrored. Check the listing title for the side and for whether a bracket is included.
Remanufactured and new calipers are separate listings and are never priced the same. Remanufactured units are cleaned, honed and fitted with new seals; read the description to see what the supplier replaces.
If a caliper is replaced because of a leak, the hose and the fluid should be replaced as well, otherwise the new seals see the same contaminated fluid that destroyed the old ones.