Romeo and Tybalt did not duel. They fought. A duel is much more formal and is a prearranged meeting, generally on an isolated ground. The Capulets and the Montagues were in the middle of a low grade interfamily war. For an illustrative example, see West Side Story, based on Romeo and Juliet.

Saw the Central Park "Much Ado about Nothing" at the Delacorte Theater last week. Strongly recommend. The play was well staged and the only technical glitches were when the batteries went sour on the body mikes, making them cut in and out. Why they could not do quick changes on them, I do not know, as in both cases, it was relatively early in the show.