No, that poll should be illegal. This one is accurate.
The Post-Dispatch poll is consistent with the Trib poll done Aug. 13-16. In that one, it was Obama 65%-Keyes 24%. In this one, it's Obama 68%-Keyes 24%. If the candidates have done internal polling that shows differently, I haven't seen it.
http://www.chicagotribune.com/news/specials/elections/chi-0408220341aug22,1,2130462.story?coll=chi-elections-utl