As stated, there are a few accounts with modified Logins, with different display names.
Uchiha (the 6 reborn) is actually Uchiho (due to deletion issues)
To find him/identify him, you must use Uchiho (which can be confusing)
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To change login and display, It'd be a moderator nightmare.
To change only display would cause a bigger nightmare of locating characters.
(if your login name is Sasuketheawesomeuchiha, and you change display to George...nobody could find you. George wouldn't work, they would need your login name.)
See the issues?