Complex sentence: Acts that appeared on the show first were reportedly barred from appearing on Dick Clark's "American Bandstand", but if they had been on "Bandstand" first they could still be on "The Buddy Deane Show".
Split into simpler sentences: Acts that appeared on "The Buddy Deane Show" first were reportedly barred from appearing on Dick Clark's "American Bandstand". If they were on "Bandstand" first, however, they could still be on "The Buddy Deane Show".