if in a particular situation involving non-average policies where policy A has a $100 excess and Policy B has no excess, the method of apportionment is the Mean Method as commented earlier. If an average clause is incorporated in any of the policies then Independent Liability is to be adopted.
Where both policies are subject to an excess there is a complication as to the loss which has actually to be apportioned in the final payment calculation. The question is should there be a deduction of both excesses from the gross loss or should there be a deduction simply a condition of the policy which should be applied notwithstanding that the insured loss is much reduced.