by Seth Rogovoy (GREAT BARRINGTON, Mass., May 9, 2002) — Simon and Garfunkel. Loggins and Messina. Eurythmics. Hall and Oates. The pop-rock landscape is littered with the scattered remains of duos that rarely lasted a decade, much less the 20 years together that John Flansburgh and John Linnell are celebrating this year. [Editor’s note: This…