Are Kristoffer Rygg and Stevie Ray Vaughan both producers?
yes
Title: Kristoffer Rygg
Passage: Kristoffer Rygg (9 September 1976), also known as Garm, Trickster G. Rex and recently God Head, is a double Spellemannprisen-nominated and double Oslo-prize winning vocalist, musician and producer known as the frontman of Ulver as well as being former producer, lyricist and singer of Arcturus.  Rygg is noted for his multi-range singing styles and production talent in a wide array of styles, including black metal, avant-garde metal and rock, psychedelic, experimental music, ambient, electronica and film music.
Title: Stevie Ray Vaughan
Passage: Stephen Ray Vaughan (October 3, 1954 – August 27, 1990) was an American musician, singer, songwriter, and record producer.  In spite of a short-lived mainstream career spanning seven years, he was one of the most influential guitarists in the revival of blues in the 1980s and one of the greatest guitarists of all time.  AllMusic describes him as "a rocking powerhouse of a guitarist who gave blues a burst of momentum in the '80s, with influence still felt long after his tragic death."
Title: Double Trouble (band)
Passage: Double Trouble is an American blues rock band from Austin, Texas, formed by guitarist/singer Stevie Ray Vaughan in 1978.  The group was active throughout the 1980s and responsible for reviving the blues, inspiring many later blues and rock musicians.  Formed in Austin, Texas, by 1985 the group consisted of Vaughan, Chris Layton (drums), Tommy Shannon (bass), and eventually Reese Wynans (keyboards).  While with Vaughan the band was billed Stevie Ray Vaughan and Double Trouble.  Rooted in blues and rock music, the group worked in many genres ranging from ballads to soul, often incorporating jazz and other elements.
Kristoffer Rygg Stevie Ray Vaughan