User blog:AlexSmasher/We can only vote once... per device

So apparentely we can INDEED vote for just one character in the ballot on the device we're doing it, voting multiple times only validates the last vote you submitted. For example: You vote for Bomberman first then you vote for lets say Shovel Knight. Only the vote for Shovel Knight will count. But there's the posibility of voting from a different device if you want to vote again for another character. Either way, I'll try this method to vote again for the first 2 characters I already voted for.

Source: https://twitter.com/wiidude83/status/583666945586757633