Definition of "Duplicate" :

noun: a copy that corresponds to an original exactly

"He made a duplicate for the files."

noun: something additional of the same kind

verb: increase twofold

verb: make or do or perform again

verb: make a duplicate or duplicates of

"Could you please duplicate this letter for me?."

verb: duplicate or match

adjective: being two identical

adjective: identically copied from an original

"A duplicate key."