accomplishedToday, I decided to look up sheet music for each song. (And in the process learned that "Heart & Soul" was written by Hoagy Carmichael, with lyrics by Frank Loesser, for the 1938 Paramount short, "A Song is Born"--not to be confused with the feature-length 1948 RKO movie of the same title that starred Danny Kaye.)
And as it turns out, I was both right and wrong; mostly the latter. The two songs definitely have separate origins, but use the same chord progression (I-vi-IV-V or I-vi-ii7-V, for you music wonks out there), both "swing" their eighth notes (two eighths become a dotted eighth and a sixteenth), and, as a result, the "simple" piano accompaniment for Heart & Soul--the second piano song most people learn to play, after "Chopsticks"--is, for all intents and purposes, the basic accompaniment for "I Love the Mountains". I wouldn't be surprised if people often toss in a verse or two of "I Love the Mountains" while repeating Heart & Soul ad nauseum, just to vary things a bit, which would explain why I had the two mixed up in my head. (It looks like the melody for one can even work as a harmony/descant for the other.)
For reference, here's easy sheet music for:
Heart & Soul (for piano/voice, with more songs here)
I Love the Mountains (for voice/guitar, with more songs here)
Feudalism: Serf & Turf
