对打 = direct one-vs-one combat or sparring. Used heavily in martial-arts and action-film contexts:
对打戏 (duìdǎxì) = a fight scene. Compare with
打架 (dǎjià, to brawl, less structured),
比武 (bǐwǔ, to compete in martial arts), and
对决 (duìjué, a decisive showdown, often metaphorical).