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That's not what it means.  It means a ssn on your return has already been filed on another return.   Did you already file a return from the other account?  Could someone else maybe claimed you or your dependent as a dependent?  Or someone else accidentally typed the wrong ssn on their return and got yours by mistake.   Or you typed a ssn wrong.  If you can't find a wrong ssn on your return you will have to print and mail your return.