Okay, well, “Glenn Gould Interviews Glenn Gould about Glenn Gould.” You can find it in Tim Page’s Glenn Gould Reader, or narrated a bit in Thirty-Two Short Films About Glenn Gould. Basically, Gould interrogates himself winsomely. And I think the album Conversations with Myself, by Bill Evans, is sort of a self-interview. Evans would lay down one part of a song, play it back and record another, playing along with his previous part. A bit like that Coetzee book where each page is divided vertically between three narrators.