double feature vs doubleheader

double feature and doubleheader both are nouns.

Word	Noun	Adjective	Verb	Adverb
double feature	Yes	No	No	No
doubleheader	Yes	No	No	No

As nouns, double feature and doubleheader are synonyms defined as:

double feature and doubleheader: two games instead of one (especially in baseball when the same two teams play two games on the same day)

Other synonyms of double feature include twin bill.

double feature (noun)	doubleheader (noun)
two games instead of one (especially in baseball when the same two teams play two games on the same day)	two games instead of one (especially in baseball when the same two teams play two games on the same day)