Where an agent stands in the situation of a mere middleman, not having undertaken to act as agent for either party or to exercise his skill, knowledge or influence, but merely to bring the parties together to deal for themselves, he may recover from each, but to stand in the position of a middleman he must have limited his services to the bringing of the parties together, and where the broker, in disregard of his duty, conceals an adverse interest or secretly enters into the service of another, he not only forfeits his right to commissions, but must account for gains unlawfully acquired, etc. Schmidt v. Wallinger, 99 S. E. 680, 125 Va. 361.