duplicate
duplicate — verb
1. to produce a second item that is exactly the same as the original, such as a doc
to produce a second item that is exactly the same as the original, such as a document, a key, a digital file, or a piece of art.
Élise used the office scanner to duplicate the contract before mailing it.
duplicate + direct object (document)
The museum allowed researchers to duplicate old photographs from the archive.
duplicate + from [source]
Christopher duplicated the apartment key at the hardware store on Prince Street.
The technician duplicated the entire project folder onto a backup drive.
duplicate + onto [destination]
Every page in the damaged manuscript was duplicated by Lakshmi using a flatbed scanner.
passive: be duplicated by [agent] using [tool]
- duplicate a document
- duplicate a key
- duplicate a file
- duplicate from the original
- duplicate onto a disk
Grammar Patterns
duplicate + [noun phrase]
Usage Note
The object is typically a concrete item (document, key, photo) or a digital entity (file, folder). Use 'from' to indicate the source and 'onto' or 'to' for the destination medium.
Common Mistakes
2. to carry out the same task, action, or process a second time, especially when do
to carry out the same task, action, or process a second time, especially when doing so is wasteful or serves no additional purpose.
Noa duplicated her report because she forgot she had already submitted it online.
duplicate + work already done
Joaquín duplicated the same calculation error across three columns of the spreadsheet.
duplicate + mistake (unwanted repetition)
Linh worried that the new marketing proposal would duplicate the campaign from last quarter.
duplicate + earlier work (redundancy)
The new scheduling system prevents teams from duplicating each other's maintenance tasks.
prevent + duplicating + [noun phrase]
Caleb realized the two departments were duplicating the same customer survey work.
- duplicate effort
- duplicate work
- duplicate a task
- duplicate a mistake
- avoid duplicating
- avoid
preventing unnecessary repetition is the opposite of creating it
Grammar Patterns
duplicate + [noun phrase (effort/work/mistake)]
Usage Note
Common in workplace contexts with words like 'effort,' 'work,' 'task,' and 'mistake.' Carries a negative tone of wastefulness or oversight. Distinguish from sense verb/1: here the focus is on unnecessary repetition, not on creating an exact copy.
Common Mistakes
3. to become twice as large in number, amount, or size, or to cause something to re
to become twice as large in number, amount, or size, or to cause something to reach twice its previous level.
The company's annual revenue duplicated in the two years after the merger with SunCorp.
intransitive: revenue duplicate (increase twofold)
Ayana's workload duplicated when two senior nurses left the paediatric ward unexpectedly.
The population of the coastal town duplicated between 2010 and 2020 as new factories opened.
intransitive: population duplicate over time
The manufacturer duplicated its output by adding a second assembly line at the factory.
transitive: duplicate + output (deliberate increase)
- duplicate output
- duplicate revenue
- duplicate population
- duplicate in size
- duplicate over time
- double
the everyday word; 'double' is far more common than 'duplicate' for this sense
- increase twofold
more formal; often used in academic or business writing
- halve
to reduce by half — the direct opposite of doubling
Grammar Patterns
duplicate + [noun phrase]
[noun phrase] duplicate (intransitive)
Usage Note
Considerably less common than sense verb/1. Used in formal or statistical writing about business, population, or production metrics. The intransitive use ('revenue duplicated') is the most frequent pattern. 'Double' is the everyday alternative.
Common Mistakes
duplicate — adjective
1. describing something that matches the original in every detail, so that the two
describing something that matches the original in every detail, so that the two items are indistinguishable from one another.
Rania kept a duplicate set of wedding photos at her mother's flat in Taipei.
duplicate + set of [items]
The duplicate key opened the back gate without any trouble at all.
duplicate + key (common collocation)
Min found a duplicate invoice in the folder and threw the extra one away.
The hotel receptionist handed Christopher a duplicate room card during check-in.
attributive: duplicate before noun
A duplicate licence was issued after Aylin reported her original one stolen.
passive: duplicate licence issued
- duplicate key
- duplicate copy
- duplicate document
- duplicate receipt
- duplicate licence
- original
the first version from which duplicates are made
Grammar Patterns
duplicate + [noun]
Usage Note
Almost always used before a noun (attributive position). Common with items that can be easily copied: keys, documents, cards, files, receipts. Not used with a complement (*'this key is duplicate').
Common Mistakes
2. having two parts that are the same in shape, size, or design, usually because th
having two parts that are the same in shape, size, or design, usually because they are intended to form a matching pair.
The twins wore duplicate outfits on their birthday to surprise their classmates.
The architect placed duplicate stone pillars at both ends of the courtyard garden.
duplicate + plural noun (paired items)
The two guest rooms on opposite ends of the hall have duplicate furnishings and layouts.
The software generates duplicate windows so users can compare data side by side.
duplicate windows (matching interface elements)
- duplicate pillars
- duplicate windows
- duplicate rooms
- duplicate copies
- duplicate sets
Grammar Patterns
duplicate + [plural noun]
Usage Note
Less common than the adjective sense about copies. Typically describes paired architectural features, symmetrical designs, or matching sets. Often interchangeable with 'matching' or 'identical' in such contexts.
Common Mistakes
duplicate — noun
1. a physical or digital item that has been made to be exactly the same as another
a physical or digital item that has been made to be exactly the same as another item, usually to serve as a replacement or backup.
This painting is a duplicate of the one hanging in the Musée d'Orsay.
a duplicate of + [original]
Caleb made a duplicate of the spreadsheet before applying any formula changes.
The librarian found a duplicate of the rare Japanese map in the basement storage room.
find a duplicate of + [specific item]
Aylin stored a digital duplicate of her passport in a secure online folder.
digital duplicate (common with files)
The restaurant kept duplicates of all reservations from the previous week for reference.
duplicate + of + [plural noun]
- a duplicate of
- keep a duplicate
- make a duplicate
- store a duplicate
- digital duplicate
- original
the first version from which duplicates are derived
Grammar Patterns
a duplicate of + [noun phrase]
Usage Note
Typically used with 'of' to indicate the original ('a duplicate of the key'). Often implies the duplicate is kept as a backup rather than for everyday use. Do not confuse with 'copy,' which is more general — a duplicate is always an exact replica.
Common Mistakes
2. a situation in which a document exists in two identical copies, typically one fo
a situation in which a document exists in two identical copies, typically one for each party involved, or one for filing and one for reference.
Please fill out this customs form in duplicate and keep the yellow copy for yourself.
fill out [form] in duplicate
The visa application must be submitted in duplicate with two recent passport photographs.
submit [document] in duplicate
All sales invoices should be prepared in duplicate for the tax office and the customer.
The tenancy agreement was signed in duplicate so each party kept a copy.
sign [agreement] in duplicate
- in duplicate
- fill out in duplicate
- submit in duplicate
- sign in duplicate
- prepare in duplicate
- in two copies
a clearer but less formal alternative; 'in duplicate' is the standard phrase in official English
- in triplicate
same idea with three copies instead of two
Grammar Patterns
in duplicate
Usage Note
Used only in the fixed phrase 'in duplicate,' which follows verbs like 'fill out,' 'submit,' 'prepare,' 'sign,' or 'issue.' Common in official, legal, and administrative contexts. Never used as a standalone noun; not 'the duplicate' for this sense.
Common Mistakes
3. an extra copy of a collectible item — such as a stamp, a book, or a coin — that
an extra copy of a collectible item — such as a stamp, a book, or a coin — that is already present in a collection and is therefore surplus to requirements.
Tara traded her duplicate stamp from the 1963 set with a collector in Kyoto.
duplicate + collectible item (stamp)
The antiquarian bookshop sold its duplicate of the first-edition novel at auction.
Anjali brought her duplicate copy of the cookbook to the community book swap event.
duplicate copy of + [book]
Coin collectors often catalogue duplicates separately and use them for trading with others.
duplicate (noun) in collecting context
- sell a duplicate
- trade a duplicate
- duplicate stamp
- duplicate book
- duplicate coin
- extra copy
more general; 'duplicate' is the precise term in collecting circles
- surplus copy
formal; emphasises that the item is not needed
- missing item
a collectible that the collector needs and does not yet own
Grammar Patterns
a duplicate of + [collectible noun]
Usage Note
Specialised vocabulary used in the context of collecting. A duplicate in this sense is not just a copy — it is an unwanted extra of something a collector already owns. Often appears alongside 'swap,' 'trade,' 'exchange,' or 'sell.'
Common Mistakes
Word family
- duplicationnounC1
- duplicatornounC1
- duplicativeadjectiveC1
- duplicitynounC1
Synonym discussion
Sense: verb/1
All four words describe creating something that resembles an original, but they differ in exactness, register, and domain. 'Copy' is the everyday, all-purpose word — you copy a file, a drawing, or someone's hairstyle — and it does not guarantee perfect fidelity. 'Duplicate' is more formal and specific: it means creating an exact, usually official replica (a duplicate contract, a duplicate key). 'Replicate' has a scientific or technical tone; scientists replicate experiments, and manufacturers replicate production processes — the emphasis is on reproducing a result faithfully. 'Reproduce' is the broadest of the group, covering everything from photocopying (a reproduced document) to biological reproduction (organisms reproducing). 'Clone' comes from biology and computing: a clone is genetically or digitally identical. In everyday use, 'copy' is the safest choice; 'duplicate' suits formal and administrative contexts; 'replicate' fits technical writing; and 'clone' is reserved for precise identity in biology or software.
Common collocations
Nouns
- duplicate copy
- duplicate key
- duplicate file
- duplicate document
- duplicate form
- duplicate effort
- duplicate work
- duplicate stamp
Adverbs
- exactly duplicated
- carefully duplicated
- unnecessarily duplicated
- accidentally duplicated
Phrases
- in duplicate
- exact duplicate
- near duplicate
- duplicate record
Prepositions
- duplicate of
- duplicate from
- duplicate onto
- duplicate in
Etymology
The word 'duplicate' comes from Latin 'duplicatus,' the past participle of 'duplicare,' meaning 'to double.' This verb was formed from 'duplex' ('twofold'), which itself combines 'duo' ('two') and 'plicare' ('to fold'). The idea is of folding something to create two identical layers. English borrowed the word in the 15th century, first as an adjective and later as a verb and noun. The core image of 'folded double' still underlies all modern uses: something that exists in two matching copies.