My question is can a spouse have insurance coverage through his employer and be added to my companies plan as well? That would mean that he has coverage through his own company and through mine, giving him dual coverage.
Typically a person would only need one policy that counts as minimum essential coverage under ObamaCare, but can have more than one if they choose.
In fact, there are a few scenarios in which it makes sense to have "dual health insurance coverage."
For example, when a family has two very good employer plans due to both spouses working, when a person has access to both Medicaid and Medicare, or when it makes financial sense to pair an existing individual/family or employer policy with a new individual/family or employer policy (this would have to be a very specific case to make sense).
With private plans, the plan with the oldest policyholder birth date is designated the “primary plan”, while the other is designated the “secondary” plan. With Medicare and Medicaid, Medicare is the primary payer for most services, and Medicaid covers benefits not offered by Medicare.
Generally, the insurers will coordinate benefits, so it makes it simple on the policy holder's part.
Claims can be submitted to both policies, and this allows the plan holder to take advantage of the policy offering the best deal.
That being said, this setup only makes sense in specific cases (such as when at least one plan is subsidized by an employer or the state).
The reason this is true is because all plans are subject to the same out-of-pocket maximums, and thus there is only so much you can spend with any one plan in-network (and in some cases out-of-network). Also, every plan is subject to deductibles, thus you have to spend down a certain amount on a given plan before its full range of cost-sharing benefits kick in.
Given the above, it would rarely make sense to hold two high deductible plans, but would make sense to hold two employer subsidized low-deductible plans with lots of differing benefits (especially true since employers can essentially penalize you for not taking their plan).
In short every situation is different, but the bottom line is having two plans is an option that makes sense in some situations, but you only need one.
If you choose one plan, you should generally aim to pick the one with the best coverage that you think you will keep for a full policy period. In cases where you have dual coverage, the insurer will do most of the work.