how to upload two files on same form different path in codeigniter

if($this->input->post('Submit')){

//-----------Image File Section Start Here -----------//

 $config['upload_path'] = './uploads/';   // Directory 
$config['allowed_types'] = 'jpg|jpeg|bmp|png';  //type of images allowed
$config['max_size'] = '30720';   //Max Size
$config['encrypt_name'] = TRUE;   // For unique image name at a time

$this->load->library('upload', $config);  //File Uploading library
$this->upload->do_upload('userfile');  // input name which have to upload 
$video_upload=$this->upload->data();   //variable which store the path

//--------------End of Image File  Section------------------------//



//---------Thumbnail Image Upload Section Start Here -----------//

$config2['upload_path'] = './thumb/';   // Directory 
$config2['allowed_types'] = 'jpg|jpeg|bmp|png'; //type of images allowed
$config2['max_size'] = '30720';   //Max Size
$config2['encrypt_name'] = TRUE;   // For unique image name at a time


$this->upload->initialize($config2); //we can not use upload library again and again it will not initialize again and again so thats why i have used initialize 
$this->upload->do_upload('txt_thumb');  // File Name
$thumbnail_upload=$this->upload->data(); // store the name of the file 

//--------End of Thumbnail Upload Section-----------//



    $date=date("d-m-Y");  // Store current date in variable 

   // Here the database query to insert

    $data = array(
    'parent_id'=> $this->input->post('txt_parent'),
    'cat_id' => $this->input->post('txt_category'),
    'title'=> $this->input->post('txt_title'),
    'status' => $this->input->post('txt_status'),
    'featured' => $thumbnail_upload['file_name'],
    'image' => $video_upload['file_name'],
    'time'=>$date
    );

       $sql_ins= $this->Insimage->insertimage($data);
       if($sql_ins)
       {
           $data['Success'] = "Image has been succesfully inserted!!";
       }