It is very tough to fix now honestly... I think best solution is to remove old options manually.
The code to fix Polls is as follow, but it works only on old DB, it would mess up everything on IP 2.0.
##### POLL CONVERSION - BEGIN
# Table: 'phpbb_poll_options'
CREATE TABLE `phpbb_poll_options` (
poll_option_id tinyint(4) DEFAULT '0' NOT NULL,
topic_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL,
poll_option_text text NOT NULL,
poll_option_total mediumint(8) UNSIGNED DEFAULT '0' NOT NULL,
KEY poll_opt_id (poll_option_id),
KEY topic_id (topic_id)
);
# Table: 'phpbb_poll_votes'
CREATE TABLE `phpbb_poll_votes` (
topic_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL,
poll_option_id tinyint(4) DEFAULT '0' NOT NULL,
vote_user_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL,
vote_user_ip varchar(40) DEFAULT '' NOT NULL,
KEY topic_id (topic_id),
KEY vote_user_id (vote_user_id),
KEY vote_user_ip (vote_user_ip)
);
##ADD
ALTER TABLE `phpbb_topics` ADD `poll_title` varchar(255) DEFAULT '' NOT NULL AFTER `topic_type`;
ALTER TABLE `phpbb_topics` ADD `poll_start` int(11) UNSIGNED DEFAULT '0' NOT NULL AFTER `poll_title`;
ALTER TABLE `phpbb_topics` ADD `poll_length` int(11) UNSIGNED DEFAULT '0' NOT NULL AFTER `poll_start`;
ALTER TABLE `phpbb_topics` ADD `poll_max_options` tinyint(4) DEFAULT '1' NOT NULL AFTER `poll_length`;
ALTER TABLE `phpbb_topics` ADD `poll_last_vote` int(11) UNSIGNED DEFAULT '0' NOT NULL AFTER `poll_max_options`;
ALTER TABLE `phpbb_topics` ADD `poll_vote_change` tinyint(1) UNSIGNED DEFAULT '0' NOT NULL AFTER `poll_last_vote`;
UPDATE phpbb_topics t, phpbb_vote_desc vd
SET t.poll_title = vd.vote_text, t.poll_start = vd.vote_start, t.poll_length = vd.vote_length, t.poll_max_options = 1, t.poll_vote_change = 0
WHERE t.topic_vote = 1
AND vd.topic_id = t.topic_id;
INSERT INTO `phpbb_poll_options`
SELECT vr.vote_option_id, vd.topic_id, vr.vote_option_text, vr.vote_result
FROM `phpbb_vote_desc` vd, `phpbb_vote_results` vr
WHERE vr.vote_id = vd.vote_id
ORDER BY vd.topic_id ASC, vd.vote_id ASC, vr.vote_option_id ASC;
INSERT INTO `phpbb_poll_votes`
SELECT vd.topic_id, vv.vote_cast, vv.vote_user_id, vv.vote_user_ip
FROM `phpbb_vote_desc` vd, `phpbb_vote_voters` vv
WHERE vd.vote_id = vv.vote_id
ORDER BY vd.topic_id ASC, vv.vote_user_id ASC;
##REMOVE
ALTER TABLE `phpbb_topics` DROP `topic_vote`;
DROP TABLE `phpbb_vote_desc`;
DROP TABLE `phpbb_vote_results`;
DROP TABLE `phpbb_vote_voters`;
##### POLL CONVERSION - END