It's just confusing... people always think a username is unique. Having multiple @jack's is bad UX.
Discussion
some people would rather not use their real names though
Thank you
I use "display" name (doesn't need to be real) and it doesn't create the expectation of uniqueness
how do your mentions appear inline, with display_name ??
💯
What’s the best way to pull your name up in Damus when typing a note? That’s all that matters here for client compatibility.
display_name is an unspec’d damus field meant for just a way to show a real-name on your profile, the fact it is now required for cross-compatible mentions is a bit annoying.
As an @jack…I agree
On Bogbook awhile back I had someone coming on and identifying as @ev, which looked exactly the same as my handle, which is @ev, and then pretending to be me while I was sleeping.
The solution I came up with was to provide a small in-line public key hint:
After I did that whoever it was cut it out, because everyone could see he had different public key than my own.
Impressive 
Jack with a Spanish accent sounds like hack 🤔