Have Sonya Scarlet and Serj Tankian both been singers in a metal band?
Sonya Scarlet: Sonya Scarlet (born 2 April 1980) is the singer and lyricist of the Italian extreme gothic metal band Theatres des Vampires. Serj Tankian:  He is best known as the lead vocalist, songwriter, keyboardist, and occasional live rhythm guitarist of the metal band System of a Down, formed in 1994.
yes