A duet between a man and a woman usually involves the former singing the lower-pitched parts while the latter performs the higher, but this pair does things a bit differently.
Moscow-based Juliana Strangelove is a contralto, meaning she has the lowest vocal range among female singers. Arthur Vasiliev is a countertenor, meaning his is among the highest male singing voices. But when the two perform together, it’s hard not to assume that each of their individual voices belongs to the other.
In the video below, Strangelove and Vasiliev lip-sync to the song they recorded together beforehand to avoid the guitar overpowering their voices. The difference in pitch is definitely a little jarring.