It's really easy to make mobile install twice the same game/app you just need to edit(ex. using notepad) jad file of game/app and change value of "MIDlet-Name:"
Example:
Install iTunes Revolution first time so jad file will have:
MIDlet-Name: iTunes Revolution
And when you want to install other it again just edit
MIDlet-Name: iTunes Revolution_2
But if you meant how to use dual Corelet(iTunes, MV, Virtual Corelet) you need to unload already loaded Corelet
for Itunes
just press "0"
for MV
Menu->Media Viewer->Unload->Yes
for Virtual Corelet
Menu->Unload
To load another corelet you need to make shortcut to it or patch your mobile with patch called "Reflect corelet in the list java.fpa"
You can download it here(46R and 49R):
DOWNLOAD