The killers in the Kenyan village singled out non-Muslims, shooting them point-blank or slitting their throats, just like the previous night in an adjacent hamlet.
A Somali extremist group claimed responsibility but Kenya's president blamed local political networks for the 60 deaths.
President Uhuru Kenyatta, in a national address, said evidence indicates that the motive for the killing spree was to evict a community of people in order to grab the land along the coast near the Somali border.
He said al Shabab, a Somali group linked to al Qaeda, was not behind it.
But analysts expressed doubt. Matt Bryden, the former head of the UN Monitoring Group on Somalia, said al-Shabab has never claimed credit for an attack it didn't carry out.
"It has all the hallmarks of an al Shabab attack, said Bryden, now the head of Sahan Research.
"Secondly, there's been no sign of a Kenyan group carrying out an attack on this scale or with these tactics."
In a nearby village, residents stood on top of burned-out vehicles and erected barricades of burning tires to blockade the road in protest against the recent killings and what they claimed was the government's failure to provide them with enough security.
Some residents abandoned another village with their belongings on their heads while armed security forces marched in single file along narrow paths leading through the dense swamp and forest, searching for the killers.
Al Shabab said such attacks would continue "as you continue to invade our lands and oppress innocent Muslims."
Al Shabab gunmen attacked an upscale mall in the Kenyan capital, Nairobi, last September, killing at least 67 people in reprisal for Kenya sending its troops to Somalia.
The second night of deadly attacks against a Christian community on Kenya's north coast seemed designed to try to inflame Christian-Muslim tensions in Kenya, religious and political leaders said.
Bearded Muslim leaders conferring inside Nairobi's largest mosque, a grand white facade nestled among the capital's high rises, condemned what they called savage acts and ghastly killings and said there was no justification for them.
They warned of a potential sectarian rift.
"The continued violence risks tearing the country apart," they said, continuing later: "We need to be cognizant of the fact that some of these attacks are aimed at planning seeds of discord and animosity among Kenyans and divide the country along ethnic and religious lines."
Kenyatta labelled the perpetrators of the attacks as reckless hate-mongers who create intolerance and fanaticism.
Interior Minister Joseph Ole Lenku said a new slate of government and security officials have been installed in Lamu in the wake of the attacks, in part because "there seems to be some inside job."
The newer attack happened in Majembeni village, which is next to Mpeketoni, where four dozen Christian men were slaughtered.
Al Shabab said in a radio broadcast in Somalia that its fighters killed government workers and Christians.
A county commissioner, Benson Maisori, said the latest attack appeared to have been by the same group as in Mpeketoni. He confirmed 10 deaths in Majembeni.
"The style of killing is the same. They slit the victims throats wide open or shot them several times in the head," said Maisori.
Though much of Kenya's north coast has been inhabited by Muslims for centuries, Mpeketoni residents are mostly Kikuyu, a Christian community that the president hails from.
Land issues have long caused severe tension on the coast, with Muslims blaming "upcountry" Kenyans for stealing land.
Whoever was behind the attacks, the back-to-back assaults underscore the weak security around the area, which lies just south of the Somali border.
The tourist center of nearby Lamu island once attracted hordes of foreign visitors but its tourist sector has been suffering in recent years because of the violence.
Kenya has seen ethnic violence rip apart the country in recent years. More than 1,000 people were killed in ethnically motivated violence after the country's 2007 election.
Both Kenyatta and Deputy President William Ruto have been charged at the International Criminal Court for what the court's prosecutor says is their role in helping to instigate that bloodshed.