You say that the barcode was scanned at the door, and still think you could get all your friends inside using the same ticket? And how do you know any barcode

You say that the barcode was scanned at the door, and still think you could get all your friends inside using the same ticket? And how do you know any barcode you get from that website is a valid barcode? It's just a barcode, you can make one in Word if you have the right font.. Edit: Of course, having the ticket codes after eachother like that without any form of security check makes it a bad ticket system, but it doesn't necessarily lead to an overcrowded concert, just a lot of unhappy customers.