When I adopted my son, he had multiple Social Securtiy numbers. Seems some foster parents had gotten creative with their accounting. So I, not knowing this, apply for a Social Security Number for him and get notified that I have to appear in person and explain why my son has multiple numbers. Really pissed me off and I refused. They threatened litigation - big word from little clerk. I replied: "This is the number he's using. I dare you to arrest me". Several weeks later I received official notification that that number was in fact the correct one. I am still tempted to use some of the others just to see what would happen.