is CodeIgniter a good choice for Multi-site ?

What do you want to do? Do you need 2 different URL's that are in fact eachother's aliasses? Or are you planning to build two different websites (with different controllers etc.) that just share the same database and views?
So please, explain a little bit more.

Thank you so much for your answer.

Acually, I wanna use the same code to generate differents contents . and using different URL for accessing to each content.

for exemple : 

www.mysite.com/contentA  <-- I wanna buy a new domaine for it, so it will be : www.contentA.com

got it ? (sorry for my bad English  ) 

I quickly understood but it takes a long time to explain to me