The story didn't end with the movie. The TV series follows Brian Finch, who uses NZT to help the FBI. Amazon MX Player
Many viewers, particularly those with ADHD or visual processing issues, prefer dubs so they can look away from the screen without missing plot points. Others use dual audio to learn languages (watching a Spanish dub with Spanish subtitles). The "limitless" aspect allows for adaptive viewing. limitless dual audio
Not all video files support multiple audio tracks. The story didn't end with the movie