The behavior of the Resource Booking Attendant may seem confusing when it comes to processing a recurring meeting request where individual recurrences conflict with existing calendar items. Some administrators have tried working with calendar processing settings in the hopes of allowing double booking rooms with recurring meetings, as can be done with non-recurring meeting requests. As we'll see, double-booking a room with recurring meetings and the Resource Booking Attendant is impossible. If anyone's still confused hopefully this post will clear up what's going on.
Read more at source: http://msexchangeteam.com/archive/2011/02/07/457962.aspx