Are you sure? where do you found this info?
Pretty much all of Samsung's F3 line of drives use 500gb per platter, you can find that in a google search. So a 250gb version of an F3 certainly wouldn't need more than one eh?
Here's an interesting site: Just do a find-on-page for the HD253GJ and you'll see it listed in the 500gb per platter section. http://rml527.blogspot.com/2010/10/hdd-platter-database-samsung-35.html