A lender that holds a mortgage on an insured building wants its loan protected even if the owner does something wrong. The mortgage clause gives that protection.
Under the California standard fire form:
The mortgagee's interest is protected even when the insurer claims no liability exists to the owner, for example because of the owner's fraud.
If the insurer pays the mortgagee in that case, it is subrogated to the mortgagee's rights of recovery to the extent of its payment, or it may pay off the debt and take an assignment of the mortgage.
The mortgagee gets its own 10 days' written notice of cancellation.
Concurrent vs. nonconcurrent coverage: when two or more policies insure the same property on the same terms, coverage is concurrent. When their terms differ, for example only one covers windstorm, coverage is nonconcurrent, which makes it harder to divide a loss between them. The term compares policies on the same property, not policies on different buildings.