Hmm do you mean the npub? That is unique. Your display name eg 'notesbydon' is not.
Discussion
You can change your name to Jack or Disney. Multiple people can have the same display names the same time:)
Ahhhh ok. That is sad. I thought I was a genius by claiming my city's name and tweeting (sry sounds nice) like I was the mayor of the city.
@amsterdam
Jack is one of the greats though. Would love to steal his name.😉