Conn. Gen. Stat. § 9-21a

(b) Upon receipt of such list from the Secretary, the registrars may make such additional investigation as they deem necessary to determine if any elector in their town whose name appears on such list was previously registered in another town. The registrars of voters shall send to each elector on the registry list in their town, who the registrars of voters determine to be the same person who was previously registered in another town, a notice of duplicate registration in a form prescribed by the Secretary of the State stating that (1) based on a computer search of voter registration records it appears that the elector may have been registered to vote in another town before registering in the registrars' town, (2) as the result of such previous registration, the elector is no longer entitled to remain on the registry list in the previous town, and (3) unless the elector contacts the registrars of voters within thirty days to confirm that the elector is still entitled to be on the registry list in the previous town, the elector's name shall be removed from the list. The notice of duplicate registration shall include a form on which the elector may confirm that the elector is entitled to be on an active registry list because the elector is a bona fide resident of the registrars' town and either is not the person whose name appears on the registry list of another town, or has registered in the registrars' town after registering in any other town.

(c) When an elector whose name appears on the inactive list files the confirmation provided for in this section, the elector's name shall be restored to the active list. No elector shall be removed from the registry list pursuant to this section unless both registrars of voters agree that such elector has subsequently registered to vote in another town.