Short answer: Yes. You can have two plans (for example, your own and a spouse’s). Coordination of benefits rules decide which pays first; the primary plan pays as usual, and the secondary may cover some of what’s left. It does not mean double payment.
Having two health plans is common, for instance, when each spouse has employer coverage and adds the other, or when a child is on both parents’ plans. When this happens, coordination of benefits (COB) rules determine the order of payment so the plans do not duplicate benefits.
One plan is primary and pays first as if it were the only coverage; the other is secondary and may pick up some remaining cost-sharing, up to its own limits. For dependent children covered by both parents, many plans use the birthday rule, where the plan of the parent whose birthday falls earlier in the calendar year is primary. The total paid by both plans generally cannot exceed the actual cost of care.
Carrying two plans means two premiums, so weigh whether the secondary coverage is worth it. Tell each carrier about the other plan to avoid claim delays, and confirm how they coordinate, since rules differ for spouses, children, and interactions with Medicare.