In the process of buying the ticket there were no after-purchase confirmation and email (when the sale started 7 May) so I accidentally made the purchase 2 times (in fear that even king tickets will very soon be sold off). I sent an email to
pdxcon@om.events explaining this and asking for confirmation for 1 ticket and refund for second. They promiced to answer but didn't. Later I got 2 emails with ticket codes. But that's not kinda what I need.
P.S. Got the reply with a promice of refund. Looks like problem solved.