Yahoo Messenger Tweak - Multiple Login At a Time

1) Goto Start->Run, then type "regedit" (without quote) and press enter.

2) In registry editor window goto 

HKEY_CURRENT_USER->Software->Yahoo->Pager->Test

3) On the right hand side right click in the empty space and create new DWORD value.

4) Name it as Plural, set the value to 1.

5) Exit the registry editor window.

Now You can Open multiple Yahoo Messenger window,  form the each window you will able to login as a different user.