The defense that plaintiff was employed by both parties and his double employment not disclosed must, to be proved, be 624 pleaded. Childs v. Ptomey, 17 Mont. 502, 43 P. 714; Reese v. Garth, 36 Mo. App. 641; Harrell v. Bonfils Imp. Co., 45 N. Y. S. 227, 17 A. D. 405; Marks v. O'Donnell, 121 N. Y. S. 214. Compare Sec. 869.