If the main query args look like this:
'orderby' => 'meta_value_num', 'meta_key' => 'price', 'order' => 'DESC'
What orderby does the query use if the meta_key value is the same for multiple results? So, in the above example, if multiple items have the same price, how does the query order those items? Like a sub-orderby... I thought it would be publish date, but it isn't.