Wow, that's crazy. I guess it probably wasn't a computer error, more likely the trained monkeys operating the press forgot to remove one of the previous day's aluminum printing plates before putting the new ones on.
No it doesn't work that way having a separate plate for each page. Apart from the calendar on page 2 the rest of the page is okay and that would have been imposed on the press with the inside back page as it is the same sheet of paper.