Maybe it's also done on your MAC address? Try using a different computer.
I've been trying to set up multiple level 15 accounts lately so that I can start to bring in a lot of NX. I've recently tried registering using a VPN and then leveling up to 15 at which point when I try to vote it somehow knows that I've already voted on my main account which I use my regular IP for. I've also tried using TOR to register and vote on a new account which also didn't work, the site still somehow knew that I had already voted once, I'm at a complete loss as to how they're tracking whether you've voted or not. Does anyone know how to bypass this and vote on multiple accounts?
Maybe it's also done on your MAC address? Try using a different computer.
Using Tor to vote on each account should be the solution, I use it all the time. Just restart the browser after voting on each account.
I recommend buying virgin proxies. SSL Private proxy sells them, but they're are cheaper ones as well.