duplication vs gemination

duplication and gemination both are nouns.

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

As nouns, duplication and gemination are synonyms defined as:

duplication and gemination: the act of copying or making a duplicate (or duplicates) of something

duplication (noun)	gemination (noun)
the act of copying or making a duplicate (or duplicates) of something	the act of copying or making a duplicate (or duplicates) of something
a copy that corresponds to an original exactly	the doubling of a word or phrase (as for rhetorical effect)