Catalysis of the reaction: 1-chloro-2,2-bis(4-chlorophenyl)ethene + 2 H+ + 2 e- = 1-chloro-2,2-bis(4-chlorophenyl)ethane. 1-chloro-2,2-bis(4-chlorophenyl)ethene is also known as DDMU; 1-chloro-2,2-bis(4-chlorophenyl)ethane is also known as DDMS.