What is the meaning of duplicate?

noun

• Something additional of the same kind.
  • usage: "he always carried extras in case of an emergency"
  • synonyms: extra
• A copy that corresponds to an original exactly.
  • usage: "he made a duplicate for the files"
  • synonyms: duplication

verb

• Make or do or perform again.
  • usage: "He could never replicate his brilliant performance of the magic trick"
  • synonyms: reduplicate, double, repeat, replicate
• Duplicate or match.
  • usage: "The polished surface twinned his face and chest in reverse"
  • synonyms: twin, parallel
• Make a duplicate or duplicates of.
  • usage: "Could you please duplicate this letter for me"
• Increase twofold.
  • usage: "The population doubled within 50 years"
  • synonyms: double

adjective

• Identically copied from an original.
  • usage: "a duplicate key"
• Being two identical.
  • synonyms: matching, twin, twinned