duplicate

Concise Oxford English Dictionary © 2008 Oxford University Press:
duplicate

▶adjective /ˈdjuːplɪkət/ 

• 1 exactly like something else, especially through having been copied.

• 2 having two corresponding parts.

▶noun /ˈdjuːplɪkət/ one of two or more identical things. ▶verb /ˈdjuːplɪkeɪt/ make or be an exact copy of.

■ multiply by two.

■ do again unnecessarily.

– derivatives
duplicable adjective,
duplication noun.

– origin ME: from L. duplicat-, duplicare ‘double’, from duplic- (see duplex).