I have a client that just was legalized and received there social security number. The only thing is that they worked under another social security number and they have 2 W-2 forms one with the legal social security number and they other with the one they were working under. How do you do there taxes? I know you will have to use the legal social security number but how would I enter the W-2 with the other SS number? 

Last year they went with someone else and they had the W-2 under the social security number they were working under and when they went to do the taxes the Tax representative used the legal social security number for the tax return but the W-2 has another. They now received a letter that they will not receive the refund because the records don't match what the IRS has. 

This is a very touchy situation and i want to make sure i am doing this correctly.