It is asked thousand times.Yes ... they display different ads - then using chitika won't decrease Adsense ctr(premium).
adsense best of the best but i banned=(some asshole made clicks to my ads. i think second after adsense is YahooPN but its only for USA. if you not from USA only adbrite. chitika earnings Impressions Clicks CTR eCPM Revenue 257 5 1.95% $0.82 $0.21 five clicks 21 cent=) kaman bebi kaman!
I prefer Chitika over adsense on my niche product sites. The Chitika ads seem more relevant for my specific niche than adsene & users definatly click these ads.
They'll be displaying different advertisements. So, yes, you can use both of those on your website, blog.