No, I really don't. I just heard a dixie version of Midnight in Moscow several times as a child, my father had it in some collection LP, so maybe it was the same version. But I didn't listen to any version when I played this, it was by 'dixie feeling'. So I'm quite sure the improvisations of clarinet and trombone cannot be identical to any original. But certainly I had the idea of this song as a dixie in mind from havinv heard it as a child ;-)