If i have one adsense account and 2 blogs, i can place ads on both of blogs with one adsense account i mean i have to get different ads or i can copy the first one?
you can copy the first code, however to do it in a good way, i suggest you to get a new code under a different channel. That way, you can track your earnings better. Note: you don't need another adsense account, one account is all you need to put the ads code in as many sites as you wish...
you have 3 different options. you can either use the same code if you want. or if you want to track your earnings per domain or even per ad unit, you can either setup an URL channel or an ad unit channel