No, the poll you're referring to is the PPP/Kos poll, which is as Leftie as it gets, and the results were clearly skewed to convince the gullible (Akin, Huckster, et al) that Akin should stay in.
The Mason-Dixon poll is quite reliable, and unfortunately, predicts a pretty easy reelection for Frau McCaskill. But hey, at least the Huckster's folks are happy!
They won by losing.. How I don’t know...