This defense, double employment, may be proved under a denial of all the allegations of the complaint except that plaintiff was a broker. Wolf v. Demboskey, 74 N. Y. S. 465, 36 Misc. 643, 66 A. D. 428; Nichols v. Greenstreet, 130 N. Y. Sup. 843, 71 Misc. Rep. 196, judg. aff. 131 N. Y. Sup. 1131, 140 App. div., 940; Biggins v. Pottman, 174 P. 119, - Cal. App. - .