Yes, you can. The e-file system has no way of knowing what W-2s have been filed for you. Your return should get accepted and processed. However, if you don't amend in a timely fashion, you will get a correction notice from the IRS (CP2000). If it's a W-2 and there was withholding taken out, there's a good chance it will not cause any major repercussions such as tax owed, penalties, and interest.
