Is it legal to have your own health insurance through your employer as well as being on your spouse's employer's health insurance plan?

Yes, but check into them carefully first. Both me & my husband both have insurance coverage on us and our kids. I did not realize it but it is hurting us more than helping us at the moment. My insurance is not as good as my husbands and my birthdate falls earlier in the year. My husbands insurance has a "do duplication of benefits clause in it" which means when they figure up what they pay they figure out their normal amount they would pay subtract off what my primary insurance paid and then pay the difference which is little to nothing. What is really hurting us is that they have larger discounts than my primary and so when they would have paid all of it had they been primary but pay nothing since they are secondary we are stuck to foot the bill (last one was $483.00). Unfortunately I cannot drop my insurance and my husband cannot drop his because of clauses that state that if your spouse has insurance available to them from their employer that they much take it. However, I am going to drop mine to a basic single plan (the smallest I can get) and let my kids just be covered under my husbands which will save us money in the end ( I hope unless there is something else I don't know about), Unfortunately I cannot do this until next January (I just found out about the discounts thing) when my company allows changes to insurance plans. Yes. One is primary, one is secondary. Primary is usually whose birthday comes first in the year. The birthday rule only applies when there are dependants involved. The primary insurance is always the insurance for the company you work for. If your spouse has his/her own coverage, there health insurance from their company will be their primary and yours will be the secondary.