PREFIX dc10:  <http://purl.org/dc/elements/1.1/>
PREFIX dc11:  <http://purl.org/dc/elements/1.0/>
PREFIX my: <http://www.example.org/my#>

SELECT ?title ?author
WHERE    { { ?book dc10:title ?title; dc10:creator1 ?author }
         UNION
         { ?book dc11:title ?title; dc11:creator2 ?author }
       }