I believe you can (Voting Booth poll) vote as many times as you like, but only your first vote counts toward the results.

Update: Well, mischief - I sit corrected.   A while back I noticed almost the same thing, except I could vote several times from the same IP and only the first counted.   Either vroom tweaked the Voting Booth a bit, or I'm delusional.   I hope those two are mutually exclusive {grin}
    cheers,
    Don
    striving for Perl Adept
    (it's pronounced "why-bick")