Do multiple Python interpreters on a server share pages in memory?
This is an operating system feature (not a language feature) that at least Linux and probably most OSes offer. It's nothing unique to Android.
So yes, Python and multiprocessing do essentially the same thing if you are running on Linux, simply because they use fork() to spawn additional processes.
One of the more clever things Android does to conserve memory and increase startup time is share pages between multiple Dalvik interpreters by forking processes from a the zygote process. When an application loads, the static, readonly library code pages are shared between the parent and the child. 
Does python or multiprocessing do anything on these lines?