The principal having employed the broker should give him a fair chance to accomplish his work. He cannot capriciously terminate the employment while the negotiations are being carried on, but the broker having had a fair chance and failed, or having abandoned his efforts, the principal is free to treat with the same customer, either directly or through another broker without liability to the first broker. An owner may employ several brokers to sell the property and the first one who succeeds gets the reward. He may negotiate with purchasers himself and may sell without the help of any broker. An exclusive agency prevents the owner from employing other brokers, but does not prevent a sale through his own efforts free from claim of commission unless the terms of the exclusive agency provide otherwise.