I appear to have acquired an extra double ticket (one ticket, valid for two people -- so not splittable) for Erotica. The ticket is valid for any day of the show (but presumably only one day, IYSWIM).
Since I already have tickets but don't have much in the way of money, I'm selling this double ticket for just £15. That's two tickets for the price of one, basically. Bargain! Go on, you saucy people, you know you want to.