Nontypicall array comes in php after the submission.I wrote a small function to restate it to the familiar look.
<?php
function multiple(array $_files, $top = TRUE)
{
    $files = array();
    foreach($_files as $name=>$file){
        if($top) $sub_name = $file['name'];
        else    $sub_name = $name;
        
        if(is_array($sub_name)){
            foreach(array_keys($sub_name) as $key){
                $files[$name][$key] = array(
                    'name'     => $file['name'][$key],
                    'type'     => $file['type'][$key],
                    'tmp_name' => $file['tmp_name'][$key],
                    'error'    => $file['error'][$key],
                    'size'     => $file['size'][$key],
                );
                $files[$name] = multiple($files[$name], FALSE);
            }
        }else{
            $files[$name] = $file;
        }
    }
    return $files;
}

print_r($_FILES);
/*
Array
(
    [image] => Array
        (
            [name] => Array
                (
                    [0] => 400.png
                )
            [type] => Array
                (
                    [0] => image/png
                )
            [tmp_name] => Array
                (
                    [0] => /tmp/php5Wx0aJ
                )
            [error] => Array
                (
                    [0] => 0
                )
            [size] => Array
                (
                    [0] => 15726
                )
        )
)
*/
$files = multiple($_FILES);
print_r($files);
/*
Array
(
    [image] => Array
        (
            [0] => Array
                (
                    [name] => 400.png
                    [type] => image/png
                    [tmp_name] => /tmp/php5Wx0aJ
                    [error] => 0
                    [size] => 15726
                )
        )
)
*/
?>