semi mistaken identity

I was visiting JHU APL to get ideas for a Science Operation Center for our new project at work, and was getting badged in, and the guard said "Oh, you are already in the system", to which I said I didn't know how I could be, but ok. So he does the name, employer, check, then he asks for the last 4 digits of my social. So I rattled them off, and he asked me to repeat them, so I did, and it became apparent there was a disconnect between the answer I was giving, and the answer I was expecting. He starts with the name thing again and goes "And you are Firstname C. Lastname" to which I go "No, I'm Firstname S. Lastname".

So, there is at least one other Fed guy running around with my name. Be afraid. Be very afraid.