If your two W-2s were from the same employer, one of them may have been a corrected W-2. There is a box, usually toward the top of the form, that states it is a corrected form.
If one of the W-2s is a corrected form and that is the one that you used when you filed your return, then you do not need to do anything further.
Otherwise, if you need to include the second W-2 as part of your return or make a correction to the information that you already filed, you will need to file an amended return as stated by robtm.
See the following TurboTax help article for more guidance about filing an amended return:
How do I amend my federal tax return for this year?
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