Jimmie Ross is an American rock guitarist and vocalist who is best known for being a member of Pittsburgh band the Jaggerz, known for their 1970 hit "The Rapper".
 During the band's initial existence of 1965-1976, the bassist shared the duties of lead vocalist with guitarist Donnie Iris.
 By the time the Jaggerz regrouped in 1989, Iris was well into his solo career, and Ross became the sole lead vocalist and remained bassist.
 He continues to hold both positions today.
"Overkill" is a song by Australian pop rock band Men at Work.
 It was released in 1983 as the second single from their second studio album, "Cargo" (see 1983 in music).
 It was written by lead singer Colin Hay.
 It peaked at No. 3 on the "Billboard" Hot 100; No. 5 on the Australian Kent Music Report Singles Chart; and top 10 in Canada, Ireland, and Norway.
 The song was a departure from the group's style of reggae-influenced pop rock, featuring a melancholic feel musically and lyrically.
Colin James Hay (born 29 June 1953) is a Scottish-born, Australian-American musician and actor who performed as lead vocalist of the band Men at Work, and later as a solo artist.
Topanga is the fourth solo album by Scottish-Australian singer Colin Hay, released in December 1994.
 (See 1994 in music).
 According to Australian musicologist, Ian McFarlane, it "sold well in Canada, Germany and Brazil.
 In July, Hay set off on his solo Man at Work Australian tour."
Peaks & Valleys is the third solo album by Scottish-Australian singer Colin Hay, released in 1992.
 Hay recorded each song in one take.
Company Of Strangers is the seventh solo album by Scottish-Australian singer Colin Hay.
 It was released in 2002 on Hay's independent record label, Lazy Eye.
Gathering Mercury is the eleventh studio album by Colin Hay, released on May 9, 2011, on Compass Records.
 Regarding the album's thematic content, Hay said, "I think it’s about life and loss and the injustice of the way the universe is set up; how we lose people we love."
"Everything I Need" is a song by the Australian group Men at Work.
 The song was written by Men at Work singer/guitarist Colin Hay and the recording was produced by Hay with keyboardist Greg Ham.
 It was released in 1985 as the lead single from their album "Two Hearts".
Men at Work were an Australian rock band best known for their 1981 hit "Down Under".
 Formed in 1978, their founding mainstay was Colin Hay on lead vocals; he formed the group with Jerry Speiser on drums and Ron Strykert on lead guitar.
 They were joined by Greg Ham on flute, saxophone, and keyboards and John Rees on bass guitar.
 This line-up achieved national and international success in the early 1980s.
 In January 1983, they were the first Australian artists to have a simultaneous No. 1 album and No. 1 single in the United States "Billboard" charts – "Business as Usual" (released on 9 November 1981) and "Down Under" (1981), respectively.
 With the same works, they achieved the same distinction of a simultaneous No. 1 album and No. 1 single on the Australian, New Zealand and United Kingdom charts.
 Their second album, "Cargo" (2 May 1983) was also No. 1 in Australia, No. 2 in New Zealand, No. 3 in the US, and No. 8 in the UK.
 Their third album, "Two Hearts" (3 April 1985), reached the top 20 in Australia and top 50 in the US.
Full Circle is the debut album of Pittsburgh rock/pop musician Jimmie Ross, best known as a member of the Jaggerz.
 The album, released in 2010, contains the best of his songs from the Jaggerz.

Question: Were Jimmie Ross and Colin Hay both lead vocalists in their bands?
Answer: yes