Man, that's a great choice and a very obscure film by today's standards. Most don't even recognize it as a Spielberg film. Underrated is hard because it can mean so many things. There's a film I love that, in a way, is a little bit like Duel, called "The Slender Thread." Entire film takes place while a volunteer worker at a suicide hotline tries to keep a suicidal woman on the line long enough for authorities to reach her. Another I adore is called "Resurrection" with Ellyn Bursten (1980). There's another, newer film by that name that has nothign in common except the title.