
If you’ve got many Gmail accounts and don’t want to keep logging on and off them every time you switch, a simple command line parameter in the Google Talk shortcut can solve your problem.
First method:
- First, create one copy of the Google Talk shortcut on your desktop – leave the original intact.
- Right click on this shortcut and choose Properties. The Target box will show you the path of the EXE for Google Talk – something like “C:\Program Files\Google\Google Talk\googletalk.exe”
- Change this to: “C:\Program Files\Google\Google Talk\googletalk.exe” /nomutex and click OK.
screen shot
After that login to multiple accounts. See the screen shot

And second method is :
Open chat from browser and the other chat from the Gtalk, which is really a better way to open 2 account at the same
time.

