I was covered by two insurace companies, one by my work place and one by my husbands. I did not understand that I was covered by my work place. I thought I signed up to be able to file for health insurance for my family if my husband lost his job. I didn't understand that I should have been using both insurance companies and have been turning in claims, only to my husbands policy. I found out today that I have been covered by my work health insurance also. What will happen when the first insurance company finds out that I was also covered by another company and didn't file claims with both. Will I be in trouble?
It would have saved me money if I had realized I should have been filing for both. I am afraid I will owe my husbands insurance company the money my insurance company might have paid on me.

Chances are nothing will happen. One policy (probably your husbands) was your primary policy and the other (yours) most likely your secondary policy. Whatever the primary policy does not cover, the secondary usually picks up.

The above is correct. The only thing that might cause you a problem is if the opposite happened and your work insurance got a claim (as your secondary) only to learn that you have another (primary) insurance that would have paid the bill. Since it did not happen this way, you have nothing to worry about.
It's a good idea to check with the HR department to verify this and be sure. They won't report you, only answer your questions. You could also discuss options with them so when open enrollment occurs, you might be able to negotiate your plan for a lower rate since its only secondary coverage.

Most likely, your work has you as the primary and your husband is a secondary. All that should happen here is that your husband's carrier will contact your carrier for reimbursement of the moneys they should have paid. Let the two carriers work it out.

The only way you would be in trouble is if you filed claims with both as if they were the primary.

Well first don't expect it to save you a lot of money,

If and when you have a claim your insurance ( though your work) will be primary and pay first, if there is anything not covered, you can turn it into the second. But both will have their deductables and co pays. So often if your husband is paying a lot a month to have you covered, what they will pay will seldom be as much as you pay for coverage, unless you have a lot of medical bills