Double where dan and di codeigniter

public function ambil_pesan($username,$to_username,$table)
{

$result = $this->db->select('*')
->where('username',$username)
->where('to_username',$to_username)
->where('status','pesan terkirim')
->or_where('username',$to_username)
->where('to_username',$username)
->where('status','pesan terkirim')
->order_by('tgl_pesan','desc')
->limit(10)
->get('tb_pesan');

return $result->result();
}