At the moment I have 2 x google adsense on my site in positions which I expect to get the most clicks. I am thinking to add more ads to my site but from another providor, is this ok??

Im thinking to add 2 more ads (In the footer and in the bottom of the sidebar ) I dont expect to get many clicks on these ads so would it be best to go for a cpm providor?? Or would it be best not to even add these ads??

Thanks