Supporting a petition requires staking a block.
Let suppose I have enough clamcoins to catch stacking block. If I vote for petition with my staking amount then send all my clams to poloniex or JD then remove client, intstall it again, change IP (another proxy) send my clammies back to new wallet and try to vote same petition again? Will it be counted?
IP has nothing to do with it.
Every 1 minute (on average), "someone" has a chance to stake a block. You have a bigger chance the more coins you have available to stake.
That is what is counted.