When I add an HTML description to my event page and then click the "preview" button, I get an event page that has the HTML description and then the plaintext description - it displays both instead of overriding the plaintext description - so it looks like the info is just repeated.
Also, every page I create already has "allow HTML description" checked by default, and uses an old HTML description from one of the first events I ever created on the calendar. Every time I create an event, I have to go in to the event page and UNCHECK "allow HTML description" if I don't want every single event page to have the same description (a description from a very old event)!!