It is possible to run several instances of Yahoo! Messenger using a tiny registry tweak.
Create a file named “yahoo.reg” and copy and paste the following inside it :
REGEDIT4 [HKEY_CURRENT_USER\Software\yahoo\pager\Test] "Plural"=dword:00000001
Save the file and double click on it , windows asks for a confirmation to write the data inside windows registry , click on Yes.
We are all set 🙂