Every policy of insurance and every guaranty contract or surety bond covering the liability of the employer for compensation shall cover the entire compensation liability of the employer to his employees, and shall contain a provision setting forth the right of an employee to enforce in his own name, either by at any time filing a separate claim or by at any time making the surety a party to the original claim, the liability of the surety in whole or in part for the payment of such compensation, provided, that payment in whole or in part of such compensation by either the employer or the surety shall, to the extent thereof, be a bar to the recovery against the other of the amount so paid.