Multiple instances of Yahoo Messenger

Simple way to do this is:

• Go to START->RUN-> Type 'regedit' and press ENTER.
• Then navigate to 'HKEY_CURRENT_USER\Software\Yahoo\Pager\Test'
• Now in the right pane right click New->DWORD Value. Name it as 'Plural'.
• Now Double click the the Plural DWORD you created & set the value to 1.

Now try login using two id's in a single machine.