No policy of insurance in effect on October 1, 1947, covering the liability of an employer under the workers’ compensation law, shall be construed to cover the liability of such employer under this chapter for any occupational disease unless such liability is expressly accepted by the insurance carrier issuing such policy and is endorsed on the policy. The insurance or security in force to cover compensation liability under this chapter shall be separate and distinct from the insurance or security under the workers’ compensation law and any insurance contract covering liability under either this chapter or the workers’ compensation law need not cover any liability under the other.