Plugin is causing error while activation

Hi,

I just tried to use WP-Polls 2.66 and after downloading and activating the plugin I get the following error:

Das Plugin verursachte eine Fehlermeldung 923 Zeichen unerwartete Ausgabe w?hrend der Aktivierung. Sollte du Fehlermeldungen wie “headers already sent”, Probleme mit der Syndizierung der Feeds oder andere Fehler erhalten, versuche das Plugin zu deaktivieren oder zu l?schen.

In English:

The Plugin is causing an error 923 characters unexpected output while activation. …

I am using nginx and get the following information in the error-log:

PHP message: WordPress database error Duplicate key name ‘pollip_ip’ for query ALTER TABLE wp_pollsip
ADD INDEX pollip_ip (pollip_ip); von activate_plugin, do_action(‘activate_wp-polls/wp-polls.php’), call_user_func_
array, create_poll_table

PHP message: WordPress database error Duplicate key name ‘pollip_qid’ for query ALTER TABLE wp_pollsip
ADD INDEX pollip_qid (pollip_qid); von activate_plugin, do_action(‘activate_wp-polls/wp-polls.php’), call_user_fu
nc_array, create_poll_table

PHP message: WordPress database error Duplicate key name ‘pollip_ip_qid’ for query ALTER TABLE wp_poll
sip ADD INDEX pollip_ip_qid (pollip_ip, pollip_qid); by activate_plugin, do_action(‘activate_wp-polls/wp-polls.ph
p’), call_user_func_array, create_poll_table” while reading response header from upstream, client: xx.xx.xx.xx
, server: xxx.de, request: “GET /wp-admin/plugins.php?action=activate&plugin=wp-polls%2Fwp-polls.php&_wpnonce=
c6251d95fb HTTP/1.1″, upstream: “fastcgi://unix:/var/run/php5-fpm.sock:”, host: “xxx.de”, referrer: “https://xxx.de/wp-admin/update.php?action=install-plugin&plugin=wp-polls&_wpnonce=36ddc171c9”

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