Hmm.
I have a 2-CD set, that was recorded and burned from the West Coast broadcast the night the concert was performed, and I have cassettes that I recorded myself, from the East Coast broadcast the next night, and I never noticed a difference in the sound of Stevie's vocals from one night to the next... and I usually have a good ear for these things.
'Welcome To My World' is definitely overdubbed... Stevie was having some kind of bronchial/asthmatic problem the night of the show, so she overdubbed most of her vocals for future broadcasts.