The incident happened on Thursday night in Lodhna village near Khandaghosh when Sheikh Fazle Haq and Dukhiram Dal were returning home after polling duty.
"They were attacked by armed men last night and subsequently succumbed to their injuries. No arrests have been made so far," Superintendent of Police Gaurav Sharma said.
The twin killings follow the murderof another Marxist activist, Tahidul Mandal, in Domkal town of Murshidabad district on Thursday during the third phase of the state assembly polls.
The CPI-M has alleged that the Trinamool Congress is behind the killings, a charge denied by the ruling party.
"Haq and Dukhiram's son were our polling agents. They were killed by Trinamool. The frustration of the Trinamool losing ground continues," said CPI-M state secretary Surya Kanta Mishra.
"The gruesome killing of our comrades in three days proves how unnerved the Trinamool has been. The killings are the outcome of its increasing fear of impending defeat," added Mishra, who is also leader of opposition in the outgoing assembly.
Rubbishing the charges, the Trinamool leader from Khandaghosh, Uttam Sengupta, said the twin murders were a result of "factional feud within the CPI-M".
Incidentally, the killings came on a day when Prime Minister Narendra Modi, campaigning in the state, said polls in Bengal are in the news for violence.
"Unlike other states, the only news that one hears about polls in Bengal is how many people were killed, how many were beaten, or how many booths were looted," Modi said at election rally in Howrah on Thursday. (IANS)