Select Join for two columns in codeigniter

I have got answer

$this->db->select('t1.product_name,t1.location, CONCAT(t2_1.first_name, " ", t2_1.last_name) AS added_by, CONCAT(t2_2.first_name, " ", t2_2.last_name) AS updated_by');
$this->db->from('Table 1 t1');
$this->db->join('Table 2 t2_1', 't2_1.id = t1.added_by', 'left');
$this->db->join('Table 2 t2_2', 't2_2.id = t1.updated_by', 'left');
$query = $this->db->get();
return $query->result();