Is there any good reason to have do-over "wedding" 16 months after eloping?

The only explanation for this extremely rude behaviour is that the couple realised they missed out on the presents and the general "being centre of attention for a day" when they chose to elope, so now they are staging a fake re-do wedding as if their first wedding never happened. Not only is this tacky beyond belief, it is also an insult to the intelligence of their guests who know very well that this wannabe bride has been a matron for over a year. Don't go, send a book on etiquette as a gift.