使用tmp名称保存上传的文件

Is it a good practice to keep an uploaded file with it's tmp_name? Check the following example:

$short_tmp_name = substr($_FILES['tmp_name'], -6)
move_uploaded_file($_FILES['file'], "$uploads_dir/$short_tmp_name");

When handling file uploading like in above example:

1. Will name collisions happen?
2. Does this practice reveal any security issues?

EDIT:

I've clarified the question(modified the code example).

there is no issue as such, but to be on safer side and handle error, do something like shown below. NOTE : Just a sample code, add more error/other checks and handling based on your need

$error = '';

if ($_FILES["file"]["size"] == 0) {
    $error = 'Uploading failed';
} 
else if ($_FILES["file"]["size"] > MAX_UPLOAD_FILE_SIZE) {
    $error = 'File size exceeds ' . MAX_UPLOAD_FILE_SIZE_MB;
} 
else if ($_FILES["file"]["error"] > 0) {
    $error = 'Error while uploading';
}

if(!$error) {
    $file_name = $_FILES["file"]["name"];

    if (file_exists(DESTINATION . $file_name))  {
        $path_parts = pathinfo($dstFile . $file_name);
        $file_name = $path_parts['filename'] . '-' . time() . '.' . $path_parts['extension'];
    }

    $dstFile = DESTINATION . $file_name;

    if (move_uploaded_file($_FILES["file"]["tmp_name"],$dstFile)) {
        //its done
    }
    else {
        $error = 'Unexpected system error';
    }
}