There are multiple users of he same SSAN. The IRS is trying to determine which one is the real American -usually when a significant return is expected.. I had something like this when I had a large return coming. She asked questions about my pension distributions, what I filed two or three years an the light bulb clicked and she said, “your return will be issued in 10 days.’
Well, since the Government allowed other to “use my SSN”, then I thought at least one of them would file the tax return! I suggest you go after them for failure to file and not me since you cannot tell who I am for refund purposes….