Is it okay to have different Adsense code on different sites that are hosted on the same server? I would never have two different Adsense codes on the same site. But I am hosting different websites for people and each site would have a different Adsense account. Is that okay?
Yes, you can use the same Adsense code over multiple pages, even if they are not hosted on the same server. But in this way, you can't use custom channel to check the performance of each unit.