I believe you were referring to this, so correct me if I'm wrong:
张无忌一面躲闪,心下转念:“我只逃不斗,岂不是输了?这太极拳我还不大会使,且以挪移乾坤的功夫,跟他斗 上一斗。”一个回身,双手摆一招太极拳中“野马分鬃”的架式,左手却已使出乾坤大挪移的手法。
While dodging, Zhang Wuji thought: “If I keep running without fighting, wouldn't that be losing? Since I'm not yet proficient at Taiji Fist, I'll have to use Qian Kun Da Nuo Yi.”
He turned around, both hands executed Taiji Fist's defensive stance “Wild Horse's Mane”. His left hand unleashed Qian Kun Da Nuo Yi techniques. (From dgfds01's translation)
If it is, then you must know, it was only the posture that resembled Taiji, and he did it with both hands. What really happened was that he was using mainly his QKDNY techniques to fend off his opponent's moves. It was not the combined effort of both skills which brought Ah San under control.
It was stated that ZWJ could understand all internal energy cultivation thanks to 9 Yang, and his QKDNY helps him to understand all(?) physical attacks. Which of the above category do you think L/R technique falls under?however, during the battle at Brightness Peak, he himself was able to see the kungfu styles of Wudang 1st hero and White eagle king, but he did understand the basics or the logic behind their movements due to the art of 9yang... so he might not be able to understand the basis of the L/R technique...