When any employer is insured against liability for compensation with any insurance carrier and such insurance carrier shall have paid any compensation for which the employer is liable or shall have assumed the liability of the employer therefor, it shall be subrogated to all the rights and duties of the employer and may enforce any such rights in its own name or in the name of the injured employee or his personal representative; provided, however, that nothing in this section shall be construed as conferring upon insurance carriers any other or further rights than those existing in the employer at the time of the injury to his employee, anything in the policy of insurance to the contrary notwithstanding.