I know it's about the blackface - but maybe the Eastern European caricature, while perhaps much less offensive to most of us, isn't really all that much better? Just a thought.
The Don Carlos duet *also* doesn't really make much sense because it's not from the opera in question. (But it's certainly easier to sing than "Si Pel Ciel" from Otello lol.) But as I said, at least it's Verdi. It seems to me it would make even less sense in the Pagliacci context.