I have faced double-ticketing twice here. The first time I was lucky coz I reached early and could reserve my rightful seat. But the next time, someone else was already perched on my seat number and I had to spent the first 20 minutes of the movie on the staircase till they arranged some other corner seat for me.
I later remembered that when I had gone to book the ticket in advance, the person at the window refused to show me the chart.
He assured me that it was a good seat and I didn’t argue because the queue was growing longer behind me. During the show, both the times the office was closed so I had no place to go and redress my woes.
I strongly suggest - please stand there and make the ticket seller cross out your seat number on the chart right in front of your eyes. This applies to any theatre!
Cheers!