Conditional statements and common categories

I use this

query_posts(‘cat=63,50’);

to display posts that belong to either/or all these categories.

In a certain block I want to display items which are common to BOTH these two categories.

I am using

if ( in_category(’50’) || in_category(’63’) );
$posts = get_posts(‘numberposts=5’);
if( $posts ) :
foreach( $posts as $post ) : setup_postdata( $post );
**** SHORT BODY TEMPLATE STUFF ****
endforeach;
endif;

DOESN’T WORK.

This displays posts from ALL categories on the site.