Nam, in a pair with Alberto Lim of the Philippines, defeated Japanese duo Sora Fukuda and Renta Tokuda 6-3, 6-2.
Itis the second time the duo claimed a title at a junior tournament. Thefirst was at the Sarawak Chief Minister"s Cup in Malaysia last month.
Earlier, the Vietnamese, who is seeded No 1 in both singles and doubles event, entered the final of the boys' singles.
He trounced Yosuke Watanuki of Japan 6-2, 6-2 to set up a trophy match against Renta Tokuda, another Japanese.-VNA