Double fugue
DEFINITION
Properly, a fugue which has two separate subjects that are both treated fugally; a proper double fugue should consist of two different themes, introduced separately, which eventually are combined so the second theme forms a countersubject. The term double fugue has also been applied to a fugue in which the theme and countersubject appear simultaneously at the beginning of the composition and are regularly associated throughout.a fugue with two themes that occur at the same time