Hej! Check out the total amount printed on the receipt (kvittering) than you can at least see what you actualy paid for. There you'll also find other information which will help you to get your ticket. I wouldnÃ‚Â´t be too worried.
BUT; to be honest I got a bit worried about the extra show. I donÃ‚Â´t like the idea of playing an extra show at the same day, too much. Performing with an orchestra takes quite some focus I believe and to do that twice within a couple of hours seems to me a bit much (It's like playing the champions league semi-final games in one go!).
Maybe they are getting into it even more the second concert, who knows. Only way to find out is by attending both shows, which I will do (as well as probably all the 2500 other visitors!!!).
And magically we will reach the 3,5 hours which is nontheless the standart time for a good italian opera.