It was a phenomenon that seemed more common the late 1970s / early 1980s, I think. A single would be released for participation in the airwaves sweepstakes, and then if & when it really made it big, a new – different, LONGER – version would be released and from then on that would be the version that would be played. Which, when you think about it, is kind of odd, because it was the concise original version that zoomed to popularity; why assume people would even LIKE the version with the additions? (Although I have to admit the extended versions are often really nice).
Anyway, it seems like an interesting category for list compilation, so add the ones you know of.
Here are three to get started:
#1
Manfred Mann’s Earth Band —Blinded by the Light. The original release version available here didn’t have the slow inner section that culminates in “Mama always told me not to look into the eyes of the sun, but Mama that’s where the fun is” nor did it have the following verse about some brimstone baritone. Everything in the first linked copy of the song from about 2:37 to 5:45 (where it repeats “the calliope crashed to the ground”… except it’s repeating it from way the heck back before the new material was inserted; the phrase just sung in the longer version is “reminding him of romance!”) was definitely created post facto.
#2
Queen with David Bowie — Under Pressure. I swear the section that begins at 2:08, with a brief temporary key-change a fourth up, with lyrics “Turned away from it all like a blind man”, wasn’t originally in there. It was added later. OK maybe I’m hallucinating this one, can’t find any trace of documentation of a shorter version or a piece added, etc…
#3
Billy Idol — White Wedding. A lot was added after the song became a big hit. I sure don’t remember the instrumental interlude that begins around 3:40 or the echo-ey “rock rock rock … music music music…” and indeed here’s the original as I remember it. OK the first link is rather explicit about it being a REMIX. Truth in advertising.