It is very common thing to have more than one Email ID, and most of us also have more than one Yahoo ID. So it is a common problem of all the Yahoo users who wanted to use chat using their different Yahoo IDs together at the same time.
Official Yahoo Messenger (any version) does not enable us to do so, but we can run many yahoo messengers together easily. There are few ways to do, you may be knowing some, but here is the list of top three ways.
Download this multi_yahoo_messenger.zip file, extract it and double click the one that reads “multi_yahoo_messenger.reg” to start using the multiple instances of yahoo messenger together. Double click on another that reads “multi_yahoo_messenger_uninst.reg” to revert back to the original settings.
Just use the Y!Multi Messenger developed by John Kirchner which is the ultimate Yahoo Messenger Polygamy patch to run multiple instances of Yahoo Messenger.
Pidgin is an easy to use and free chat client used by millions. Connect to AIM, MSN, Yahoo, and more chat networks all at once.
Pidgin has hell lots of options and supports many IM clients. You should try that.
Digsby is a multiprotocol IM client that lets you chat with all your friends on AIM, MSN, Yahoo, ICQ, Google Talk, and Jabber with one simple to manage buddy list.
So go ahead and use any method to use multiple instances of Yahoo Messenger together.