The availability of refunds is determined by the organizer of the event and outlined in the site's Terms of Service. This information is always available via a link at the bottom of every page on the site. This is also found as a link in the ticket checkout before completing an order.
UPDATE: orders purchased via the Forte payment processor will no longer be able to be refunded in our system as of January 31, 2021. You can see if an order was processed by Forte by viewing the order page; the "Invoices" section in the bottom right will say "paid with Forte".
If you believe you have made a duplicate purchase, please reach out immediately to support to confirm the duplicate and provide a refund for the unintentional purchase. You can reach support via the support or chat option on the bottom right of the event's page.