An interesting question that I will admit that I haven't given much thought to. To me, I consider my real name as "Barry Melton", even though it is really "Bartholomew Melton".
I have signed contracts, purchased property and pay utility bills under the former, while the latter is relegated to a very few.
Unrelated, I think this is the first that I realized George Orwell was a pen-name.
By real names, do you mean the names they're known by, "real sounding" names or their legal names? Is George Orwell not a real name?