Is it possible to view 2 apps at the same, eg. 2 × Mail, in Split View?
This can be done only on a newer iPad or iPhone 6 Plus. running iOS 9 or higher. You will notice that these apps are not contained into 1 app, they are each running independently of the other. You can view each app and interact with each app but they can't communicate with each other (other than what's already allowed by the app itself).