Coming back to this thread because it turns out an extended version of One More Chance exists… kinda. It’s this original demo with vocals by Secret Weapon. This version is slightly longer than the MJ version and has more of the horns at the end. The horns at the end don’t really change, they just play the same riff 3x times before the song fades out, unlike the MJ version where they’re only heard once before the fade out.
There’s also some more vocals/ad libs at the end not present on the MJ version (who knows, maybe MJ did record more vocals but they faded out before we could hear them). This version of the song has a drum machine and is pitched down a semitone.
Turns out R Kelly wrote the song for this band named “Secret Weapon”. Their record deal fell through and all their stuff was unreleased, so R Kelly gave the song to MJ. R Kelly also had his own writers demo of the song that likely predates this version by Secret Weapon, but that is yet to be leaked (but R Kelly’s original demo vocals were accidentally used in the Ford remix of One More Chance). I know it’s not exactly what the original poster was after, but you get to hear more of the horns that they were wanting to hear. It also reveals that the horns didn’t really go any further melodically and just replayed that same riff several times.