Searching custom fields

I’m creating a movie review website using WordPress. In order to display Cast, Director and Screenplay details for each movie, I’m using custom fields. I’ve noticed that the search function doesn’t search these, only the post itself.

So if I’ve reviewed a film starring Robert De Niro and someones searches for him, chances are the search would come up with nothing, even if I’ve reviewed a film starring said actor.

I worked around this using a <div id=”moviedetails”></div> in my actual post with the actor’s, director’s names etc. contained within. I then set it to display:none; in my stylesheet, thus making it invisible to the user. Searches for actor’s names then work.

The thing is, I’m then essentially doubling up on cast details on the finished page. Although users only see one lot of cast details, search engines will see it twice.

I’m just wondering if the workaround I’ve devised would mean me being penalized by the major search engines, making for lower rankings. Or does it not work like that?