The only way someone could vote twice is with 2 different accounts to login. As far as I know, I'm the only one with multiple accounts (Rhapsody #348, J/30 and Bill is Testing). I only voted with the Rhapsody account.
from a sampling standpoint - 50 respondents is actually pretty good on a statistical poll. Of all the J/30 owners, there are 235 registered with forum accounts.