'Additional insured' coverage and multiple insurers: resolving overlapping coverage disputes
Insureds which suffer a loss may find that they are covered by multiple insurance policies for that loss. Such situations can arise inadvertently, or the existence of multiple overlapping policies may be by design. A number of issues may arise with the duty to defend, where there are overlapping or concurrent insurance policies – for example, how courts resolve overlapping or concurrent coverage absent a clause in one or more of the policies that deals with the issue.
Source: internationallawoffice.com