1) Bicephalus 2) Diplocephalus 
conjoined twins with two heads
Congenital malformation resulting in the development of two heads. 
Symmetrical conjoined twins with two separate heads. ... See: conjoined twins. ... Synonym: bicephalus, diplocephalus. ... Origin: G. Di-, two, + kephale, head ... (05 Mar 2000) ... 
(di-sef´ә-lәs) a malformed fetus with two heads; called also bicephalus and derodidymus.
Type: Term Pronunciation: dī-sef′ă-lŭs Definitions: 1. Symmetric conjoined twins with two separate heads. Synonyms: bicephalus, diplocephalus See: conjoined twins, under twin
derodidymus; dicephalus A malformed fetus with two necks and heads, but a single body and normal limbs.