In 2009, a man arrived at the world-famous Sun Studio in Memphis, TN for a private tour. He told David Brookings, the young, aspiring musician giving the private tour, that his name was Steve Eason. David had been briefed that Eason was a big figure in the music industry, very famous, and so Sun would have to be very careful to preserve his privacy. Eason was also darn ill; he'd been hooked up to some gear that followed him around the studio.
The kid had never heard of Steve Eason, but he gave a passionate tour. At the end, David handed Steve a CD with music on it, hoping to land a record deal. A month later, Brookings got a message from Apple, asking him to come join iTunes to curate Rock & Roll playlists.
And Steve Eason? He wasn't a musician, or even a record producer. The man receiving the Sun Studio tour was Steve Jobs, who had been in Memphis to receive a kidney transplant for pancreatic cancer. He was staying in a house bought by a man named Eason, but Eason was - in fact - the doctor Jobs had scheduled to perform the transplant surgery.
Brookings has worked at Apple to this day.
In truth, more people go by alias names than you'd expect. Without checking a driver's license (and, depending on the sensitivity, maybe some utility bills), you may never know if someone is who they say they are.
Also, I have friends I've met offline, who have moved around to different countries and swapped devices. It's always a big pain trying to establish trust once your physical relationships go digital. There are only so many challenge-response questions to ask them (i.e., things only the two of you know). In reality, our digital and offline lives are intermingled; they each inseparably affect the other, and sometimes it feels like identity problems are turtles all the way down.