How to orderby my custom post type with two custom meta keys

I am working on real state property website. I have CPT “soto_property”. I also have two custom fields for this CPT named “price” and “dorm_room”. I have a search form, from where visitor can filter properties with different price and dorm_room.

So what I want is that if visitor search for 2 dorm_room, IT SHOULD SHOW ALL THE 2 dorm_room 1ST IN PRICE ORDER FROM HIGH TO LOW AND THEN 3 dorm_room FROM HIGH TO LOW price and THEN 4 DORM ROOM WITH HIGH TO LOW PRICE .

I have followed many links shown below but no luck –

http://www.billerickson.net/code/order-results-multiple-meta_keys/
https://gist.github.com/lolitaloco/5441726

here is my code-

$properties = array(
    'post_type' => 'soto_property',
    'paged'=>$paged,
    'posts_per_page' => 6,
    'order'     => 'DESC',
   'orderby'    => 'meta_value_num',
    'meta_key'  => 'price'

);

/*check Price range */
if (!empty($_GET['price_range'])) {
    $lowestPrice=get_post_meta($_GET['price_range'],"lowest_price",true);
    $maximumPrice=get_post_meta($_GET['price_range'],"maximum_price",true);
    $properties['meta_query'][] = array(
        'key' => 'price',
        'value' =>  array($lowestPrice, $maximumPrice),
        'type' => 'numeric',
        'compare' => 'BETWEEN',
    );
}



/*check bedrooms range */
   if (!empty($_GET['bedrooms'])) {
        $beds_value=get_post_meta($_GET['bedrooms'],"beds_value",true);
        if($beds_value)
        {
            $properties['meta_query'][] = array(
            'key' => 'dorm_room',
            'value' =>  $beds_value,
            'type' => 'numeric',
            'compare' => '>='
            );

        }
    }

 function orderbyreplace($orderby ) {
     global $wpdb;
             return ('mt1.meta_value DESC, mt2.meta_value DESC');
}
add_filter('posts_orderby','orderbyreplace');

query_posts($properties);

remove_filter('posts_orderby','orderbyreplace');

This code sorts property posts by price from High to low but not with dorm_room.