Duet

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mid 18th century: from Italian duetto, diminutive of duo ‘duet’, from Latin duo ‘two’.

wiktionary

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From Italian duetto(“short musical composition for two voices”), diminutive of duo(“two”).

etymonline

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duet (n.)

"musical composition for two voices or instruments," 1740, from French duet, from Italian duetto "short musical composition for two voices," diminutive of duo "two" (from PIE root *dwo- "two"). The Italian form of the noun was used in English from c. 1724. As a verb, "to perform a duet," from 1822. Duettino "short, unpretentious duet" is by 1839.