S.C. Code Ann. § 29-3-20: Prior mortgages may be redeemed by second mortgagees.

If it so happen there be more than one mortgage at the same time by any person to any person or persons of the same lands and tenements, the several mortgagees who have not registered or recorded their mortgages, their heirs, executors, administrators or assigns, may redeem any former mortgage registered upon payment of the principal debt, interest and cost of suit to the prior mortgagee, his heirs, executors, administrators or assigns.