I've been to quite a few weddings where there was a super formal meal at 6 to go along with speeches and that part of the evening, then around 9:30 or so, second dinner was served and was usually sandwiches, dessert trays, greasy finger foods, and the like. Definitely a big hit, especially when a lot of folks have been drinking for a good portion of the day and they need something in their bellies to help absorb it all :)