So you didn't finish up registration first time, but it remembered your data when you tried from a normal browser?
That's what I assume, because I got a message saying that someone had already registered from that IP address. And of course it wasn't the IP address, because I had never registered before and Tor's IP address was completely different from mine.
When I tried Tor, it asked me to complete some captchas that I couldn't, and then with the other browser it didn't ask me.
Didn't experience this kind of issue but its really crazy that their system flagged that even if your first registration didn't push thru. It seems that they have sensitive system and automatically flagged their site visitors or users IP to avoid multi accounting issues.
I know this is common suggestion but I think its better to talk about this matter on their support. Try to raise this issue to their support so that they would also know your situation and to make sure that your account created is clean so that you won't encounter any possible issue link to multiple account usage.