The Peanuts Biography (Wikipedia)
The Peanuts (ザ・ピーナッツ Za Pīnattsu) were a Japanese vocal group consisting of twin sisters Emi Itō (伊藤エミ, Itō Emi) and Yumi Itō (伊藤ユミ, Itō Yumi). They were born in Tokoname, Aichi, (Japan) on April 1, 1941. Soon after the twins' birth, the family moved to Nagoya. Their uniqueness was their being monozygotic twins, with voices only slightly apart in timbre which resulted in their singing together sounding like a solo artist using double tracking or reverb).