The highest single limit, not a sum of vehicles
Alaska's rule is in the Mandatory Automobile Insurance Act. AS 28.22.221 caps the payable amount at the highest limit of any one coverage when two or more vehicles are insured under one policy, and AS 28.22.201 sets the exhaustion, rejection and unknown-driver rules. The older AS 28.20.445 holds the damages-minus-payments formula.
Read why Alaska does not stack coverage the way many states do, check what the two statutes say and what the courts added, or see how one combined coverage handles uninsured and underinsured drivers.