four-fold vs quadruplex

four-fold and quadruplex both are adjectives.

Word	Noun	Adjective	Verb	Adverb
four-fold	No	Yes	No	No
quadruplex	No	Yes	No	No

As adjectives, four-fold and quadruplex are synonyms defined as:

Other synonyms of four-fold include fourfold, quadruple, quadruplicate.

four-fold (adjective)	quadruplex (adjective)
having four units or components	having four units or components
four times as great or many