SailorBlue
Player Valuation: £2.5m
A "duet" only refers to the vocal parts.
A "duo" would refer to the number of people in the band, so while you're right, it's irrelevant to this thread about duets.
"Under Pressure" featured both Freddie Mercury and David Bowie on lead vocals, hence it's a duet.
Cheers mate.
I'll throw my hat in the ring for Bowie & Jagger - Dancing in the Street.