Payments under group medical policy not defense to claim for benefits. Health insurer's duty to pay. Lien

(a) Where an employer contests the compensability of an employee's claim for compensation, proof of payment made under a group health, medical or hospitalization plan or policy shall not be a defense to a claim for compensation under this chapter. (b) Where an employer contests the compensability of an employee's claim for compensation, and the employee has also filed a claim for benefits or services under the employer's group health, medical, disability or hospitalization plan or policy, the employer's health insurer may not delay or deny payment of benefits due to the employee under the terms of the plan or policy by claiming that treatment for the employee's injury or disease is the responsibility of the employer's workers' compensation insurer. The health insurer may file a claim in its own right against the employer for the value of benefits paid by the insurer within two years from payment of the benefits. The health insurer shall not have a lien on the proceeds of any award or approval of any compromise made by the administrative law judge pursuant to the employee's compensation claim, in accordance with the provisions of section 38a-470, unless the health insurer actually paid benefits to or on behalf of the employee.