I tried it, it works calling Activity_Mod_B.act_stat, so I guess the answer is:
it IS a distinct proc_global. Thinking about it, we always prefix any global by the module where it was born and resides, unless it is within the same module.
Being a lazy hack, I often create new modules by copying an existing (and proven) module - then modify to suit the new requirement. That goes for layouts as well. Give me a loaded gun and I will shoot myself in the foot until:
A) I empty the cartridge and suffer no harm..
B) The gun jams (something broke) and I must find another solution
C) I blew my foot off and must now seek professional help.
I know, the last three words from option C is your advice to me... HAHA!