I'm not surprised by that. There are quite a few casinos that turn a blind eye despite what they say in their Terms of Service. In the case of Duel, it's clear that they are even more committed to privacy, so, being aware that there is a certain risk, you should be able to bet normally. Did you use a VPN or Tor?
Duel did the right things by keeping up their promises and serving their customers frankly for privacy but with users, I really don't think betting with Tor is possible.
VPN is possible as it does provide better connection than Tor and connection speed is important for gamblers when they bet with money and need smooth experience, no lag or as least lag as possible. With Tor, connection is slow and it's impossible to have good gambling experience. I have never thought of betting through Tor connection but for other things like logging in my account and posting on the forum, I use Tor honestly.
Do you actually have any experience with Tor for gambling?