Double charges on Credit cards happen very infrequently, when it does, it is usually because of either,
(a) the user has closed the browser or clicked the back button while the credit card charge was in progress, or
(b) the third-party payment gateway that processes the credit card transaction took too long to respond and resulted in our system timing out.
Such transactions majority of the time gets failed, however, the card-issuing bank or credit card company typically puts the amount on hold and it would appear as PENDING on the statement however it doesn't mean you have been charged. The credit card company or card-issuing bank release those funds, within 2-3 business days.
By any chance, if it gets confirmed, we would encourage you to contact the event presenter to request a refund.
Note:- Yapsody doesn't handle funds and all payments are processed through the presenter's payment processor. Yapsody is not the merchant of record and has no control over the acceptance, rejection, or refund of a charge.