di-, dicho-, dich-

(Greek: number two; twice, divided, double; unalike; a number used as a prefix)

diprosopus
Two-faced conjoined twins (incompletely separated identical twins).

The twins have almost complete fusion of their bodies with one set of limbs. Part or all of the face is duplicated. The condition usually results in stillbirth.

Diptera
dipteral
Dipterocarpus
dipterology
A two-winged insect of the order Diptera, some species of which transmit arboviruses to humans.
dipterous
1. A large order of insects that includes flies and mosquitoes, characterized by a single pair of membranous wings and a pair of club-shaped balancing organs.
2. Having two wings, as certain insects, or winglike appendages, as certain fruits and seeds; such as, the dipterous fruit of the maple.
dipteryx
dipus
A fetus with dipodial symmelia (an apparent fusion of two feet).
disyllable (adjective)
dittograph (s) (noun), dittographs (pl)
1. A passage containing accidentally reduplicated syllables, letters, etc.: "Although the secretary had a terrible headache that day, her boss made her type up the letter he had dictated to her earlier. After reading it again, she found many dittographs which appeared throughout the last paragraph which had to be corrected."
2. A letter or word that is repeated unintentionally in writing or when copying written contents: "While Mary was reading through her thesis, she found some mistakes, including dittographs which somehow reappeared on every page!"
dizygotic
A reference to twins derived from two separately fertilized eggs.
multipletheism (s) (noun), multipletheisms (pl)
The belief in the existence of various gods or of many gods.