What is it called when the same property is covered by more than one policy that is not identical?

The situation described is known as nonconcurrency. This term refers to a scenario where the same property is insured under multiple policies but these policies do not provide identical coverage. Nonconcurrency arises when different insurance companies, or even different policies from the same insurer, are involved, each with their own terms, conditions, and coverage limits.

Having nonconcurrency can lead to gaps in coverage, where certain perils may be excluded in one policy but covered in another, or differences in the limits of liability that apply. It is important for insured parties to be aware of such situations, as they could potentially leave them underinsured for certain risks.

The other concepts mentioned, while related to insurance, do not describe this specific situation accurately. Duplication refers to having identical coverage in multiple policies, overlapping coverage implies that there are same risks covered by different policies but they might not be fully identical, and variance signifies differences not necessarily limited to coverage, but could also pertain to terms and exclusions.