First thing you need to do is determine if the second W-2 is a corrected W-2, and if not, why you received both.
You need to speak with your company's payroll department to be clear.
If the second W-2 is a corrected W-2, you may need to amend your tax return for the corrections made on the second W-2.
If the second W-2 is an additional W-2, you'll also need to amend and ADD the second one.
Your original return may have been accepted, but the IRS gets a copy of all W-2's generated by all employers, so if you have two, the IRS has two copies as well.
You have 3 years from the date you filed your return (or 2 years after you paid the tax due, whichever is later) to file an amended return.
Please click here for how to amend a return you already filed
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