Ghost Train registration on January 27th kind of broke the Internet! Nice work!
That said, I've had a couple of people reach out and tell me that they registered once but were double charged by UltraSignup. If this was you - and please double check your card statements to be sure - here is how you contact UltraSignup for them to investigate and resolve the problem.
I apologize if you were double charged, and although it is beyond my control to fix it, I want you to know that UltraSignup has great customer service and I hope things are fixed quickly for you. If they are not, please reach out to me at ghosttrainrace@gmail.com.
Here are the steps to contact UltraSignup: