config.inc.phpに[Second server]以下の内容を追記する
config.inc.phpについて、バージョンによってファイルのある場所が違うため注意

### Second server を追加した ###
root@hostname:/home/shimizu# vi /etc/phpmyadmin/config.inc.php
...
/* Configure according to dbconfig-common if enabled */
if (!empty($dbname)) {
    /* Authentication type */
    $cfg['Servers'][$i]['auth_type'] = 'cookie';
    /* Server parameters */
    if (empty($dbserver)) $dbserver = 'localhost';
    $cfg['Servers'][$i]['host'] = $dbserver;

    if (!empty($dbport) || $dbserver != 'localhost') {
        $cfg['Servers'][$i]['connect_type'] = 'tcp';
        $cfg['Servers'][$i]['port'] = $dbport;
    }
    //$cfg['Servers'][$i]['compress'] = false;
    /* Select mysqli if your server has it */
    $cfg['Servers'][$i]['extension'] = 'mysqli';
    /* Optional: User for advanced features */
    $cfg['Servers'][$i]['controluser'] = $dbuser;
    $cfg['Servers'][$i]['controlpass'] = $dbpass;
    /* Optional: Advanced phpMyAdmin features */
    $cfg['Servers'][$i]['pmadb'] = $dbname;
    $cfg['Servers'][$i]['bookmarktable'] = 'pma__bookmark';
    $cfg['Servers'][$i]['relation'] = 'pma__relation';
    $cfg['Servers'][$i]['table_info'] = 'pma__table_info';
    $cfg['Servers'][$i]['table_coords'] = 'pma__table_coords';
    $cfg['Servers'][$i]['pdf_pages'] = 'pma__pdf_pages';
    $cfg['Servers'][$i]['column_info'] = 'pma__column_info';
    $cfg['Servers'][$i]['history'] = 'pma__history';
    $cfg['Servers'][$i]['table_uiprefs'] = 'pma__table_uiprefs';
    $cfg['Servers'][$i]['tracking'] = 'pma__tracking';
    $cfg['Servers'][$i]['designer_coords'] = 'pma__designer_coords';
    $cfg['Servers'][$i]['userconfig'] = 'pma__userconfig';
    $cfg['Servers'][$i]['recent'] = 'pma__recent';
    $cfg['Servers'][$i]['favorite'] = 'pma__favorite';
    $cfg['Servers'][$i]['users'] = 'pma__users';
    $cfg['Servers'][$i]['usergroups'] = 'pma__usergroups';
    $cfg['Servers'][$i]['navigationhiding'] = 'pma__navigationhiding';
    $cfg['Servers'][$i]['savedsearches'] = 'pma__savedsearches';

    /* Uncomment the following to enable logging in to passwordless accounts,
     * after taking note of the associated security risks. */
    // $cfg['Servers'][$i]['AllowNoPassword'] = TRUE;

    /* Advance to next server for rest of config */
    $i++;
}

/*
 *  *  * Second server
 */
/* Authentication type */
$cfg['Servers'][$i]['auth_type'] = 'cookie';
/* Server parameters */
$cfg['Servers'][$i]['host'] = '104.155.205.9';
$cfg['Servers'][$i]['connect_type'] = 'tcp';
$cfg['Servers'][$i]['compress'] = false;
$cfg['Servers'][$i]['AllowNoPassword'] = false;
...