Both groups left the Fair but joined battle on the road outside Saphan Hin.
By the time police and Kusoldham Foundation volunteers arrived at around 10:30 pm the two gangs had dispersed, leaving four behind.
Min, 23, was already dead from stab wounds in his chest and face, apparently inflicted by a sharpened metal file.
Some 20 metres away was Min Min, 26, howling from the pain of multiple stab wounds, apparently from the same or a similar weapon. He was rushed to Vachira Phuket Hospital, but later died.
Another two were seriously injured. Moo, 24, had been stabbed in the back and Pao, 22, near the collar bone. Both were taken to hospital where they were reported to be in stable condition.
Investigators have been questioning them in an attempt to learn the names of their attackers.