Many people I meet for the first time are baffled that I don't really have a preference between being called "Dave" or "David". I went by "David" for most of my life. Then when I started working at Microsoft in the late 90s, the IT deparment there assigned me the email ID "davecort". This was the techie equivalent of immigrants getting assigned an Americanized name at Ellis Island. At Microsoft, your email ID was effectively your name. We sent so much email to each other, that was the primary name that we associated with each other, and our digital habits carried over into meatspace. Bill Gates and Steve Ballmer were always called "Bill Gee" and "Steve Bee" after their email IDs: billg and steveb.
Fast forward to 2008 and I was helping with the product vision and design for a company (Nombray) helping people manage their personal online identity. Working on that project I found another David Cortright out there who already had a reasonable web presence. Rather than competing with him for Google juice, I simply decided to go by Dave Cortright for my online identity.
My middle name is the same as my grandfather's. After Social Security was established in the 30s, every citizen had to get a card. My grandfather sent in his application with his name full name written out: "Maynard Channing Cortright". Channing was a maternal family name. His card came back, and either through poor handwriting, poor reading, or some combination of the two, the name on the card was "Maynard Stanning Cortright". He never bothered to correct it. And thus was born a new family name thanks to a transcription error at the Social Security office.