Never heard about Golden Slippers (whether "on them" or "Oh, dem") except on the soundtracks of Westerns, but I'm certain to hear "Dixie" at least once each Summer, followed by "Battle-Hymn of the Republic", since this particular medley is part of the repertoire of a regular at a pub in a village in Ireland. Probably many people sing this pairing, and no doubt there was some thought of "reconciliation" when Elvis put them together, but it's unlikely that a Civil War in another country would be foremost among listeners' thoughts when hearing songs more than a century and a half old. I can't sing the first easily, but from memory supplied the singer with a verse printed in a song-book of the late nineteenth century but never heard, as far as I'm aware:

"[two-syllable female name] married Will the weaver,
Will had a face like a butcher's cleaver, Look away! Look away...&c.

No doubt this particular combination of old songs will indeed come under scrutiny in these interesting times. I think it was one of the Adams politicians in America who considered the Slavery issue to be, as it were, "unfinished business" from their War of Independence. Sometimes, issues are not fully settled the first time round; 1789, 1830, 1848, 1870 is an interesting sequence from the eighteenth and nineteenth centuries.