As far as I know, the guitar string face on black was the shirt they used for the San Francisco run, and somewhere during the NY run they switched to the rainbow glasses John Lennon photo concept, a la the new logo. Since the show was ending, they could have run out of the new ones and sold the old ones, or who knows what.
'"Contrairiwise," continued Tweedledee, "if it was so, it might be; and if it were so, it would be; but as it isn't, it ain't. That's logic."'
~Lewis Carroll