"Most insurance policies contain 'other insurance' clauses that attempt to limit the insurer's liability where other insurance covers the same risk. Such clauses attempt to control the manner in which each insurer contributes to or shares a covered loss." Historically, 'other insurance' clauses were designed to prevent multiple recoveries when more than one policy provided coverage for a particular loss. "The application of 'other insurance' clauses requires, as a foundational element, that there exist multiple policies applicable to the same loss. " (Fireman's Fund Ins. Co. v. Maryland Casualty Co. (1998) 65 Cal. App. 4th 1279, 1304 [77 Cal. Rptr. 2d 296].)