I have adsense account. My few friends also have adsense accounts. I am doing all SEO support to all of them using my another analytic acconunt from my own PC. I setup all of these sites for that analytic account. Will it be harm to my Adsense? Please advice me.
Since all those accounts are "Linked" somehow #1 concern will be - DO NOT CLICK ON ANY ADS FROM THOSE COMPUTERS (or even attempt to cheat Google from other computers ... trust me they'll know!) other than that, i dont think you have anything to worry abt the Analytics account problem there are lots of sites with a few Analytics account which can be quite common especially when in the process of buying / selling sites, or doing SEO.
I don't think it should matter. I personally have more than one analytic account and haven't run into any problems. Analytics is jsut a tool, not like adsense where having multiple accounts is a big no no.