noun

1. One that resembles or corresponds to another; an identical copy.

   “This is a duplicate, but a very good replica.”

2. An original instrument repeated; a document which is the same as another in all essential particulars, and differing from a mere copy in having all the validity of an original.

3. A pawnbroker's ticket, which must be shown when redeeming a pledged item.

Synonyms: reproduction

verb

1. To make a copy of.

   “Can you duplicate this kind of key?”

2. To do repeatedly; to do again.

   “You don't need to duplicate my efforts.”

3. To produce something equal to.

   “He found it hard to duplicate the skills of his wife.”

Synonyms: double

adjective

1. Being the same as another; identical.

   “This is a duplicate entry.”

2. (games) In which the hands of cards, tiles, etc. are preserved between rounds to be played again by other players.

   “duplicate Scrabble”