twin vs duplication

twin and duplication both are nouns.

Word	Noun	Adjective	Verb	Adverb
twin	Yes	Yes	Yes	No
duplication	Yes	No	No	No

As nouns, duplication is a hypernym of twin; that is, duplication is a word with a broader meaning than twin:

Other hypernyms of twin include duplicate.

twin (noun)	duplication (noun)
a duplicate copy	the act of copying or making a duplicate (or duplicates) of something
either of two offspring born at the same time from the same pregnancy	a copy that corresponds to an original exactly

twin (adjective)	duplication (adjective)
being two identical

twin (verb)	duplication (verb)
give birth to twins
grow as twins
bring two objects, ideas, or people together
duplicate or match