I received duplicate W-2s from my employer. Do I file both?
Are they completely identical, box for box? If so, then you only need to file one.
If not, go ahead and enter the second W-2 except for the boxes which differ from the first one.
(Frequently, boxes 12 and 15-20 will differ on otherwise identical W-2s. In these cases, simply combine the information into a single W-2 entry.)