For them, it is a dual existence. Tamils but permanent residents of border towns in Idukki district in Kerala, they have a long history, with generations working on estates or running small businesses across the border. The way they melt boundaries, however, worry authorities during election time.

The polls are held two weeks apart in the two States — on April 10 in Kerala and April 24 in Tamil Nadu. The police worry that this gap makes double voting easy, as a good number of the Tamil population are on the voter lists of both States.

A senior police official told The Hindu on Friday that by a rough estimate, the estate areas had over 40,000 Tamil voters and checking dual voting would be a difficult task this time.

In this election, the chances of double voting are high, a trade union leader says on condition of anonymity. In Kumily, Vandiperiyar, Peerumade, Elappara, Udumbanchola, Munnar, Devikulam and other high-range towns in Kerala, political parties have been keen on utilising the dual votes, especially in the elections to the local bodies and the Assembly. The voters are paid during close contests, he says.

The Tamil voters are more affiliated to the main political parties in Tamil Nadu, and the political fronts in Kerala bring leaders of Tamil parties to win over these voters. Here, election posters in Tamil are common.

A meeting of top revenue and police officials of Theni and Idukki were held the other day in Kumily to chalk out measures to check double voting. Deputy Collector (Election) Madhu Gangadar said it was decided to monitor movements of vehicles strictly at the check-posts in Kumily, Cumbom Mettu and Bodimettu on polling days in the two States. Even routes less taken will be checked.

He said that chances of double voting in this election were less than in the local body elections. With the use of electronic voting machines, it was possible to trace the voters with the help of the voter lists.

Many estate workers and others in border towns in Idukki have their names on the voter lists of both Kerala and Tamil Nadu.