An opera piece designed to be sung by two performers is called a duet. It is a musical composition that showcases the vocal abilities of two singers who usually play different roles or characters in the opera. The duet is an integral part of the opera genre and is often used to express emotions, convey conflicts, or advance the plot. Some famous examples of opera duets include "The Flower Duet" from the opera Lakmé by Leo Delibes and "Au fond du temple saint" from the opera The Pearl Fishers by Georges Bizet.