Arefly

Redirect the user who have already login from login.php to Admin Panel.
將已經登陸的用戶從登陸頁面跳轉至控制台

No Repeat Login

Redirect the user who have already login from login.php to Admin Panel. 將已經登陸的用戶從登陸頁面跳轉至控制台

quan_flo

This plugins allows administrators to rename wordpress usernames. 
The account owner is gets a notification email about the rename process.
Install, activate, and then go to the Users->Rename Usernames menu to rename user accounts.
More about me and my plugins
Since the year 1999 I do administration, customizing and programming for several forums, communities and social networks. In the year 2013 I switched from another PHP framework to WordPress. 
Because not all plugins I’d like to have exist already I wrote some own plugins and I think I’ll continue to do so.
If you have the scope at forums or social networks my other modules might also be interesting for you. <a href="https://wordpress.org/plugins/search.php?q=quan_flo" title="ifs-net / quan_flo WordPress Plugins" rel="ugc">Just take a look at my WordPress Profile to see all my Plugins.</a> Use them and if my work helps you to save time, earn money or just makes you happy feel free to donate – Thanks. The donation link can be found at the right sidebar next to this text.

Rename Users

This plugins allows administrators to rename wordpress usernames.

No Repeat Login vs Rename Users