Votes are counted by ip address as it is the only way to know who voted without stepping into private data issues.
Because of this, in cases where the ip changes (eg. A router restart or voting from a different network) the same use r may be able to vote again.
So if you voted for example, from your home yesterday and tried again today from your office's network, you should be able to vote again.
Resetting your router is almost guaranteed to give you a different IP address.
The new widget has actually improved the voting process as the old one could allow someone to spend her votes on only one link (under specific circumstances.).
You can check all the votes if you like, if you click on the number of votes on the dashboard, after you click "view/edit links".
Each vote button displays all the IPs that voted for the specific link.
A quick way to find your own IP is to visit http://www.whatismyip.com.