This raises – and by “raises” I mean “led me to think of, off-hand, for no particular reason” - a couple of questions to which I don’t expect any answers, but find interesting nevertheless.
1. In terms of platforms, who was Lincoln closer to: Douglass or Bell? It may be that many Bell voters would have moved to Douglas in a runoff, but is that what they should have done? (Leaving aside the fact that voters don’t always do what others think they “should” do.) Lincoln and Douglas are of course associated with disagreement and debates; Bell is not really known, but both he and Lincoln were former Whigs.
2. In the 1858 Senatorial race, who would have won a direct election: Lincoln or Douglas? (The state legislature still determined Senators back then.)