For me the reason was:
- to log only Buddies messages and not IRC chats (they grow fast)
- to flash the Pidgin window only when I receive the messages from Buddies and not from IRC chats
To achieve it create a small bat file that will run second, third, ... instance of the Pidgin
set PIDGIN_MULTI_INST=1
c:\programms\pidgin2.1\pidgin -c c:\.pidgin-alt
where you need to apply paths where you installed your pidgin (in my case in programms\pidgin2.1\) after -c parameter is the path to the directory that will hold all settings for the second, third, etc... instance if this directory does not exist, it will be created)
running that bat file will run in a seperate instance and there you can make independent settings.
happy instant messaging.
chris