If you have 2 D3 keys and 2DB keys you can bot 2 sessions on same pc!
You don´t need wmware, just copy installation 2 different folder and make shortcut to diablo3.exe on desktop for each folder and in properties put -launch on "target" and start D3

(demands good cpu with good memory)
Maby you need to go in to D3 settings and out to window mode and make as small as possible, dont remember was so long ago
Hope you understand my god english
/Cirtap