The Spanish verb 'duplicar' (meaning 'to duplicate') comes from the Latin word 'duplicare' meaning 'to double'. The Latin 'duplicare' itself is a combination of two elements: 'duo' meaning 'two' and 'plicare' meaning 'to fold'. So etymologically, 'duplicar' literally means 'to fold into two' or 'to make two-fold', which evolved into the modern meaning of making a copy or duplicate of something.

Several common Spanish words share this etymology. The word 'doble' (meaning 'double') comes from the same Latin root 'duo'. The verb 'plegar' (meaning 'to fold') comes from Latin 'plicare'. You might also recognize this root in words like 'dúplice' (duplicate) and 'duplicidad' (duplicity).

Many English words are related to 'duplicar' through the same Latin roots. The obvious cognates are 'duplicate' and 'double', both from Latin 'duplicare'. The 'plic-' root meaning 'to fold' appears in English words like 'complicate' (literally 'to fold together'), 'explicit' (literally 'unfolded'), and 'pliant' (foldable, flexible). The 'duo/du-' element meaning 'two' is found in English words like 'dual', 'duet', and 'duplex'.