D.C. Code § 42-807
Sections 42-805 and 42-806 or anything therein contained, shall not extend to any case where the person or persons, against whom the redemption is or shall be prayed, shall (by writing under his, her, or their hands, or the hand of his, her, or their attorney, agent, or solicitor, to be delivered before the money shall be brought into such court at law, to the attorney or solicitor for the other side) insist, either that the party praying a redemption has not a right to redeem, or that the premises are chargeable with other or different principal sums, than what appear on the face of the mortgage, or shall be admitted on the other side; nor to any case where the right of redemption to the mortgaged lands and premises in question in any cause or suit shall be controverted or questioned by or between different defendants in the same cause or suit; nor shall be any prejudice to any subsequent mortgagee or mortgagees, or subsequent encumbrancer.
D.C. Code § 42-807