Etymology PIE word *dwóh₁ Borrowed from Latin duplicātus, perfect passive participle of duplicō, see -ate.
1
One that resembles or corresponds to another; an identical copy.
This is a duplicate, but a very good replica.
July 20, 1678, William Temple, letter to the Lord Treasurer I send a duplicate both of it and my last dispatch.
2
Law 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.
"Sir, I hope you will excuse what I am going to say; but having observed that you frequently pledge similar goods to these at our shop, which are afterwards taken out by other persons, I take for granted you are in the habit of selling the duplicates;[…]"1819, James Hardy Vaux, Memoirs of James Hardy Vaux, Vol. II, Chapter VI, p. 207:
4
The game of duplicate bridge.
The momentary madness which infects bridge players occurs frequently at rubber bridge and duplicate; and though it rarely results in murder, it often terminates marriages and close friendships[…]1999, Matthew Granovetter, Murder at the Bridge Table, page 6:
5
The game of duplicate Scrabble.
6
Biology, Botany, Natural sciences, Zoology A biological specimen that was gathered alongside another specimen and represents the same species.
Each collection, which may be a unicate or several specimens as duplicates in several herbaria, constitutes a record in the Conifer Database.2013, Aljos Farjon, Denis Filer, An Atlas of the World's Conifers: An Analysis of their Distribution, Biogeography, Diversity and Conservation Status, Koninklijke Brill, →ISBN, page 3: