Question: Are Adam Duritz and Julian Casablancas both lead singers of a band?

Context articles: One Way Trigger
The Strokes
Maria (Counting Crows)
Reptilia (song)
Julian Casablancas+The Voidz
David Bryson
Phrazes for the Young
Tyranny (Julian Casablancas+The Voidz album)
Adam Duritz
Julian Casablancas

"One Way Trigger" is a song by American rock band the Strokes.
 Written primarily by Albert Hammond, Jr. and Julian Casablancas, it was released as a free download ahead of their fifth studio album, "Comedown Machine" and was made available for streaming via YouTube and SoundCloud, and as a free download via the band's official website on January 25, 2013.
 Casablancas posted a stylized lyric sheet for the song, designed by long-time collaborator Warren Fu, on his official website on January 30, 2013.
The Strokes are an American rock band from New York City.
 Formed in 1998, the band is composed of vocalist Julian Casablancas, lead guitarist Nick Valensi, rhythm guitarist Albert Hammond Jr., bassist Nikolai Fraiture, and drummer Fabrizio Moretti.
 Following the conclusion of five-album deals with RCA and Rough Trade, the band has continued to release new music through Casablancas' Cult Records.
Maria is a recurring character in the songs written by Adam Duritz, the songwriter and lead singer of Counting Crows.
 Maria has appeared in the lyrics of five Counting Crows songs and in two other songs written by Duritz, and has fueled speculation and debate among fans.
 Duritz contends that she is fictional.
"Reptilia" is a song by indie rock band The Strokes, and the second single from their second album "Room on Fire".
 The single's B-side contains "Modern Girls & Old Fashion Men", where lead singer Julian Casablancas duets with Regina Spektor.
 The official release date was delayed slightly after Casablancas objected to the song being credited as "The Strokes and Regina Spektor", claiming that it should read "Regina Spektor and The Strokes".
Julian Casablancas and the Voidz (stylised as Julian Casablancas+The Voidz and occasionally JCVZ), or simply The Voidz, are an American rock band formed by Julian Casablancas of The Strokes.
 The band consists of Casablancas (lead vocals) as well as Jeramy "Beardo" Gritter (guitar), Amir Yaghmai (guitar), Jacob "Jake" Bercovici (bass guitar, synthesizers), Alex Carapetis (drums, percussion), Jeff Kite (keys) and Shawn Everett (production).
David Bryson (born October 5, 1961) is a guitarist and vocalist for Counting Crows.
 He was a student of guitarist Joe Satriani.
 Prior to forming Counting Crows with Adam Duritz, he produced recordings by Duritz and his band, The Himalayans, from San Francisco, California.
 He formed Counting Crows with Duritz in San Francisco in 1991.
Phrazes for the Young is the debut solo album by American songwriter Julian Casablancas, released on November 2, 2009 in the UK and November 3 in the US.
 Casablancas, who is best known for being the front man of New York rock band The Strokes, recorded the eight-song album in 2009 in New York, Los Angeles, and Omaha, Nebraska.
 Jason Lader served as producer, and musician Mike Mogis (from Bright Eyes and Monsters of Folk) contributed additional production.
 The album title is a reference to Oscar Wilde's "Phrases and Philosophies for the Use of the Young".
Tyranny is the second studio album by Julian Casablancas and the first studio album accompanied by American band The Voidz, which was released on September 23, 2014 by Casablancas's label, Cult Records.
 The first single from the album, the 11-minute track "Human Sadness", was released on September 2, 2014.
 The music video for the second single "Where No Eagles Fly" was directed by guitarist Jeramy "Beardo" Gritter.
 On September 19, "Tyranny" was made available to stream on the websites of "Rolling Stone" and Pitchfork Media.
Adam Fredric Duritz (born August 1, 1964) is an American musician, songwriter, record producer, and film producer.
 He is best known for his role as frontman and vocalist for the rock band Counting Crows, of which he is a founding member and principal composer of their catalog of songs.
Julian Fernando Casablancas (born August 23, 1978) is an American singer, producer, and songwriter.
 He is the lead vocalist of the rock band The Strokes.
 In addition to his work with The Strokes, Casablancas led a solo career during the band's hiatus, releasing the album "Phrazes for the Young" on November 3, 2009.