Under a denial of an agreement for the payment of a commission, the broker's double employment can not be proved. Mo-Fee v. Horan, 40 Minn. 30, 41 N. W. 239; Smith v. Soosan, 35 N. Y. S. 806, 24 Misc. 706; Annabil v. Traverse Land Co. (Minn. Sup. '09), 121 N. W. 233; Hoffhines v. Thorson, 141 P. 253, 92 Kan. 605.

The defense of double agency, in an action for a commission on an exchange of land, must be affirmatively pleaded. Northwest Land & Col. Co. v. Addington, 168 P. 164, 98 Wash. 576.