Users manager will not display all created users account

On Vivid 15.04 stable, plasma 4:5.2.2-0ubuntu4

If you create an account within a sudoer account like :
 john
real name: john
email: (empty)
password: john

It will work, but if then you create another account named invite with same pattern (real name, password etc), something like test, john and then close and reopen the account users configuration window : it will no longer john in the list only you and test.

I tried creating few others accounts but still one is missing.

On login screen i can see and login on the missing account from the pannel

expecting:
All existing users account should appear on the user account panel