Is there any need to use both
Is it a case that I would pick one of the two functions; is there any point in doing this after a query :
There's no need to use them both.
You should only use
wp_reset_query(), if you modified query with
query_posts() (which you should avoid). This function also call
wp_reset_postdata() - http://core.trac.wordpress.org/browser/tags/3.4.1/wp-includes/query.php#L95
So it's better to use
wp_reset_postdata() after running separate query.