"Butch and Buddy" were a pair of kid actors played by Billy "Butch" Lenhart (1930-) Kenneth "Buddy" Brown (1932-).
They appeared together in several Universal films in the early 1940s. The first pairing was in Universal's "The Under-Pup" (1939) starring Gloria Jean in her first film. They played the sons of Billy Gilbert's character.
Universal needed two young boy actors again for the zany comedy "Sandy is a Lady" (1940) starring 2-year old Baby Sandy, who was Universal's answer to Shirley Temple. Lenhart and Brown were chosen to play "Butch" and "Buddy" in the film, and this is how they got their stage names.
They were such a hit that they were paired together in several more movies over the next five years.
The first film where they were billed together as Butch and Buddy was in Spring Parade starring Deanna Durbin (read the new review here at the Deanna blog)
Their most well known films are:
"Never Give a Sucker and Even Break" (1941) with WC Fields and Gloria Jean
"In the Navy" (1941) with Abbott and Costello
After 1945 they pretty much dissovled as a comedy team, as neither had the desire to pursue film acting as a career.
Kenneth Brown appeared in only one other film after 1945, in "36 Hours" (1953) where he had a bit part as a cop.
Films with Butch and Buddy:
"Sandy is a Lady" (1940)
"Spring Parade" (1940)
"Jumpin' Jive" (1941)
"In the Navy" (1941)
"Man from Montana" (1941)
"Never Give a Sucker and Even Break" (1941)
"Doin the Town" (1941)
"Melody Lane" (1941)
"Johnny Doughboy" (1942)
"Cinderella Swings It" (1943)
"Spotlight Revue" (1943)
"A Lady Takes a Chance" (1943)
"Army Wives" (1944)
"Rough Ridin' Justice (1945) (cameo)
As of this writing, I do not know what they did after thier film career, but I am researching this.