Mine arrived today. I was going to ask if anyone knew about joint returns but my question was answered as it appears that it goes by the primary SSN. My wife's last two digits would place her refund at the end while mine is first so it appears both come in on the primary.
As I stated before, I had to return mine back to the IRS because I got taxed on imputed income ( the value of an award my wife received last year for doing well in her job) So they took all of it back plus another $113.
Easy come, easy go!