Are there any disadvantages to being covered by 2 health insurance policies?

I am currently covered by my husband's VERY GOOD health insurance. However, now that I have reached the 5-year anniversary at my current job, I am eligible to join my company's insurance for free (no premiums). The only thing is... it sucks. It's a straight PPO, no preventative care, everything covered at 80%/20%, no pre-existing condition coverage. I would like to stay on my husband's plan, but join my employer's plan as well as a back-up in case anything major happens. Can I do this? Are there any disadvantages if the "bonus" policy is completely free? Do I choose who my primary insurance is, or do the insurance companies? What else do I need to know? Thank you so much for your help.
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The insurance companies will always treat your plan as primary to you. Your husbands plan will be a back up when you exhaust your plan. There is no real good reason to do this.....As a matter of fact, this could hurt you because your benefits are less rich than your husbands.....
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