If you cannot find a legal dual audio version, consider using subtitles (SRT files) available on OpenSubtitles or Subscene, which achieve a similar accessibility goal without infringing copyright.
In the end, much like Jess on the Aeolus , you may find yourself returning to this film again and again. And with the right dual audio setup, every loop will reveal something new. Just watch out for the masked figure with the shotgun—and that haunting piano melody. Triangle 2009 Movie Dual Audio D