Codeigniter - Load, reload multiple language

Load language
english/
home_lang.php 'hello' => 'Hello'
blog_lang.php 'hello' => 'Hi'
vietnamse/
home_lang.php 'hello' => 'Xin chào'
blog_lang.php 'hello' => 'Chào'

$this->lang->load('home', 'english');
echo $this->lang->line('hello'); # Hello

$this->lang->load('home', 'english');
$this->lang->load('blog', 'english'); # will be loaded and overwrite
echo $this->lang->line('hello'); # Hi

$this->lang->load('home', 'english');
$this->lang->load('home', 'vietnamese'); # will be ignored
echo $this->lang->line('hello'); # Hello

$this->lang->load('home', 'english');
$this->lang->load('blog', 'vietnamese'); # will be loaded and overwrite
echo $this->lang->line('hello'); # Chào


$this->lang->load('home', 'english');
$this->lang->is_loaded = array();#mark no file is loaded
#$this->lang->language = array();#clean all data
$this->lang->load('home', 'vietnamese'); # will be loaded
echo $this->lang->line('hello'); # Xin chào