I think what Martjnvdc is saying is true. Some accounts on this list are not real as well https://bitcointalk.org/index.php?topic=716312.msg8900650#msg8900650
I was able to sign up as the user Degenerate. I did not know what coupons were so never tried redeeming. I even opened a ticket to dicebitco that they should stop lying as this account was never created. And the very next day the account was disabled and I couldn't log in.