Polls - browser cache clearance makes duplicate po

when a member clears browser cache, he is capable of voting for the same choice indefinite times (each time he clears browser cache). Each member is supposed to have one choice (since it is purpose of voting).

But it looks peculiar.

I tested on boonex.club

same thing is replicated.

Thank u.

Please reply for this

I understand everyone is busy.

Please reply and try fix. Otherwise it is useless module.