yes, polls are editable… see the forum – polls – manage polls admin panel…
not sure what you mean by reset… but if you mean remove votes, counts, etc, then yes on the manage poll panel… a poll will not need to be reset if you change the tracking method…
remember, if the two members are using the same computer, the cookie will be set… if they have different log ins, and you are requiring users to be logged in to vote, then the tracking can just be user id and is actually the recommendation… you would only use the other tracking options is non logged in users can vote…
why would you duplicate a poll? just put the shortcode for the existing poll into the post you want it.. seems counter productive to have the same poll, though a a duplicate, running together… if you want to restart a poll from fresh, just use the manage poll panel and clear out any votes…