Like The Duplicate, most of Sleator's works are suspenseful science fiction or fantasy that center on fairly ordinary young adults who find themselves involved in confrontations with bizarre, often hostile, beings. In Sleator's children's novel, Among the Dolls (1975), a young girl is miniaturized and threatened by her dolls, and in Interstellar Pig (1984), a young boy named Barney fights a life-and-death struggle with three aliens. In both of these works, the young characters must fight for their survival.

Rivalry between siblings, if not exact duplicates, serves as the conflict in Fingers (1983), which tells the story of two brothers who are jealous of each other's musical talents, and in Singularity (1985), in which Harry discovers how to make himself a year older than his twin brother, Barry, in order to dominate him.

The Duplicate is similar in theme to a number of works in which characters must fight their...