(a) There may be a provision as follows:

“Insurance With Other Insurers: If there is other valid coverage, not with this insurer, providing benefits for the same loss on other than an expense incurred basis and of which this insurer has not been given written notice before the occurrence or commencement of loss, the only liability for the benefits under this policy shall be for the proportion of the indemnities otherwise provided hereunder for the loss that the like indemnities of which the insurer has notice (including the indemnities under this policy) bear to the total amount of all like indemnities for the loss, and for the return of the portion of the premium paid which exceeds the pro rata portion for the indemnities thus determined.”

(b) If the policy provision in (a) of this section is included in a policy that also contains the policy provision set out in AS 21.51.200, there shall be added to the caption of the foregoing provision the phrase “ - Other Benefits.” The insurer may, at its option, include in this provision a definition of “other valid coverage,” approved as to form by the director, which definition shall be limited in subject matter to coverage provided by organizations subject to regulation by insurance law or by insurance authorities of this or any other state of the United States or a province of Canada, and to any other coverage the inclusion of which may be approved by the director. In the absence of this definition the term shall not include group insurance, or benefits provided by union welfare plans or by employer or employee benefit organizations. For the purpose of applying the foregoing policy provision with respect to an insured, an amount of benefit provided for such insured under any compulsory benefit statute (including any workers' compensation or employer's liability statute), whether provided by a governmental agency or otherwise, shall in all cases be considered to be “other valid coverage” of which the insurer has had notice. In applying the foregoing policy provision no third-party liability coverage shall be included as “other valid coverage.”