You have been the victim of identity theft. You won't be able to file your tax return electronically this year - the IRS will expect the numbers from the Health Care Marketplace to appear on your tax return.
You said you had already contacted the marketplace. Make certain that they are notified of the identity theft. Then you will need to mail in your tax return leaving the marketplace numbers off. Include a copy of the 1095-B that you received from the school district showing that you had coverage from them as well as a letter detailing the identity theft and the fact that you did not have coverage.
If you have a tax refund this is going to delay your refund significantly.
Going forward the IRS will send you a six digit identity protection PIN in January of each year. You'll need that number in order to file your tax return each year.
There are several other things that you should do to protect your identity. Here is a good article from TurboTax on tax-related identity theft.
@bram1960
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