|from eonline page: http://www.eonline.com/news/832423/everything-we-know-about-the-2017-oscars-best-picture-envelope-mix-up|
Just in from BBC News, it seems there are 2 sets of Announcement Cards per category. One would be handed out, the other that remained was a back-up card of some sort. Check out the full write-up here:
Here is Jimmy Kimmel's explanation on his night show.
Here is CNN's cover of the story
and Eonline's cover, here.
Jimmy Kimmel jokingly blamed Steve Harvey. Check out Steve's reaction here.