Duel of Karate

Duel of Karate, also known as To Subdue the Evil, is a 1971 Hong Kong martial arts film produced by and directed by Fu Ching-hua and starring Chan Hung-lit and Tien Peng as twin brothers who were separated at a young age after their parents were murdered by the chief antagonist (Yik Yuen).
Plot.
Three years ago, Iron Palm School head instructor Lung Shao-kang (Wong Chun) defeats Lei Chi (Yik Yuen) in a duel match. Three years later, Lei murders Lung after extensively training in karate. Lung's twin sons, Wei and Yu, were separated at young age as a result. Yu was adopted by Uncle Wang, a member of the Iron Palm school, while Wei was taken in by Lei. Twenty years later, Yu (Tien Peng) inherits the Iron Palm kung fu from Uncle Wang, while Wei (Chan Hung-lit) becomes Lei's right-hand man, pitting the two brothers against each other on opposite sides.
Production.
"Duel of Karate" was produced by Hong Kong's Lucky Star Films Company, but was filmed on location in Taiwan.