Can't "re-vote" when JS is turned off

Here's a strange one:

1. Turn off javascript in the browser
2. Create a new binary poll
3. Vote on choice 1 and 2
4. Cancel vote
5. Vote again on choice 1 and 2
6. -> Just a page refresh, nothing happens.

If you choose another combinations of votes, e.g just 1, the vote will go through. The critical point is when you choose the exact same choices the second time. Ajax voting seems to work without problem.