Question: Are Gaz Coombes and Petri Lindroos both vocalists?

full_context: Document 1: Eric Peterson (musician): Eric Peterson (born May 14, 1964) is an American guitarist. He is best known as the only constant member of the US thrash metal band Testament. Peterson has also formed a side project black metal band called Dragonlord, in which he plays guitar and also sings. In Testament, Peterson was originally a rhythm guitarist while Alex Skolnick handled all lead work. More recently though, Peterson plays leads along with Skolnick.
Document 2: Supergrass discography: The discography of Supergrass, an English alternative rock band, consists of six studio albums, three extended plays, two compilation albums, 26 singles and 24 music videos. They were formed in 1993 by Gaz Coombes, Mick Quinn and Danny Goffey. Rising to prominence during the Britpop era in the mid-1990s with their single "Alright", they were joined by Rob Coombes in 2002 (keyboards) until their demise on 11 June 2010.
Document 3: Paul Gascoigne: Paul John Gascoigne (born 27 May 1967) is a former England international footballer and football manager. He is also known by his nickname, Gazza. He earned 57 caps during his England career and has been described by the National Football Museum as "the most naturally gifted English midfielder of his generation".
Document 4: Jani Liimatainen: Jani Allan Kristian Liimatainen (born 9 September 1980 in Kemi, Finland) is a Finnish musician, songwriter and backing vocalist. He is the former guitarist and one of the founding members of the power metal band Sonata Arctica. He has also performed with Cain's Offering, Altaria and Stratovarius vocalist Timo Kotipelto (his band mate in Cain's Offering).
Document 5: Gaz Coombes: Gareth "Gaz" Michael Coombes (born 8 March 1976 in Oxford) is an English musician and singer-songwriter, best known as the lead vocalist and guitarist of the English alternative rock band Supergrass. He first entered the music scene aged sixteen as the lead singer of the band The Jennifers which featured Supergrass bandmate Danny Goffey. Coombes was noticeable for his large sideburns during the 1990s.
Document 6: Markus Toivonen: Markus Toivonen (born 1979 in Helsinki) is the founding member of the Finnish folk/death metal band Ensiferum. Markus founded the band in 1995 and is the sole original member to have lasted the distance to Ensiferum's present incarnation. His role in the band is guitarist and primary songwriter. He has always contributed backing vocals and since the departure of Jari Mäenpää in 2004 has taken up a greater role behind the microphone, sharing the clean vocal parts with new bass player Sami Hinkka, with Mäenpää's replacement Petri Lindroos handling the harsh vocals.
Document 7: Gazza (musician): Lazarus Shiimi, known by his stage name Gazza, is one of the most commercially successful and best selling recording artists in Namibia. Gazza was born on 10 March 1977 in Oshakati (North of Namibia) in a family of seven. At that time, he had to live in a shack behind someone's house after his father died. Despite those modest beginnings, he has always pursued the goals he had set for his life. Gazza has always loved challenges. As a soccer lover, he nicknamed himself Gazza after famous English soccer player Paul Gascoigne.
Document 8: Petri Lindroos: Petri Lindroos (born 10 January 1980 in Espoo, Finland) is a melodic death/folk metal guitarist and vocalist. He is currently the lead vocalist in Ensiferum and, prior to this, was a founder and lead vocalist for Norther.
Document 9: Supergrass: Supergrass were an English rock band, formed in 1993 in Oxford. The band consisted of brothers Gaz (guitar and lead vocals) and Rob Coombes (keyboards and backing vocals), Mick Quinn (bass and backing vocals) and Danny Goffey (drums and backing vocals).
Document 10: I Should Coco: I Should Coco is the debut studio album by English alternative rock band Supergrass, released through Parlophone in May 1995. Supergrass were formed in 1993 by Gaz Coombes, Mick Quinn and Danny Goffey and they released their debut single from the album, "Caught by the Fuzz", in May 1995 on the small independent local label Backbeat Records and was re-released with Parlophone. The title of the album is cockney rhyming slang for "I should think so".
Document 11: Aleksi Sihvonen: Aleksi Sihvonen is the current vocalist for the Finnish band Medicated. He replaced Norther's vocalist Petri Lindroos in 2009, until the group disbanded in 2012. He was also the former guitarist and vocalist of Imperanon.
Document 12: N (album): N is the fifth full-length studio album by Finnish melodic death metal band Norther. The album was released through Century Media Records on February 13, 2008 for Finland, and other dates in February for other parts of Europe. The track "Frozen Angel" from their previous EP, "No Way Back", was re-recorded for the album. "We Rock" and "Frozen Angel" have been made into music videos. This is also the last Norther album to have founding member Petri Lindroos on vocal and guitar duties.
Document 13: Here Come the Bombs: Here Come the Bombs is the debut solo album of former Supergrass front man Gaz Coombes, who performed all of the instruments on the album. It was released on 21 May 2012 by record label Hot Fruit Recordings. It charted at #54 on the UK Albums Chart.
Document 14: Timo Kotipelto: Timo Antero Kotipelto (born 15 March 1969 in Lappajärvi, Finland) is the vocalist of the Finnish power metal band Stratovarius and is the creator and vocalist of the power metal band Kotipelto. Kotipelto is currently the longest standing member of Stratovarius, after the departure of Timo Tolkki.
Document 15: The Jennifers: The Jennifers were a short-lived British rock group formed at Wheatley Park School and featuring vocalist Gaz Coombes, guitarist Nic Goffey, drummer Danny Goffey and bassist Andy Davies. Danny and Nic Goffey are the sons of former BBC Top Gear presenter and motoring journalist Chris Goffey.
ground_truth: yes