word-forming element of Greek origin meaning "two, double, twice, twofold," from Greek di-, shortened form of dis "twice," which is related to duo "two" and cognate with bi-, from PIE root *dwo- "two." In chemistry it indicates a compound containing two units of the element or radical to which it is prefixed.
before vowels, cephal-, word-forming element meaning "head, skull, brain," Modern Latin combining form of Greek kephalē "head, uppermost or top part, source," from PIE *ghebh-el- (source also of Tocharian spal "head;" Old High German gebal "skull;" also, via the notion of "front," Gothic gibla, Old Norse gafl "side of a facade").
<a href="https://www.etymonline.com/word/dicephalous">Etymology of dicephalous by etymonline</a>
Harper, D. (n.d.). Etymology of dicephalous. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/dicephalous