Lock out all WordPress Administrators except two specific users

I used the snippet below to lock out all administrators and editors except myself

if ( is_user_logged_in() ){     $  current_user = wp_get_current_user() ;     if ( in_array( 'administrator', (array) $  current_user->roles ) || in_array( 'editor', (array) $  current_user->roles )) {         if ($  current_user->user_login != 'sheila' ){             wp_logout();             return new WP_Error( 'login_again_please', 'Please log in again' );         }     } } 

When I try to add a second user in the second if statement we are both locked out:

if ( is_user_logged_in() ){     $  current_user = wp_get_current_user() ;     if ( in_array( 'administrator', (array) $  current_user->roles ) || in_array( 'editor', (array) $  current_user->roles )) {         if (($  current_user->user_login != 'john' ) || ($  current_user->user_login != 'sheila' ){             wp_logout();             return new WP_Error( 'login_again_please', 'Please log in again' );         }     } } 

How do I fix the above snippet to allow two administrators/editors with specific usernames to login or can I have an alternative with the same outcome?