That sounds like how there were two versions of MSN Messenger/Windows Messenger/Windows Live - one for 'personal' and the other for 'enterprise'. Cannot quite recall the exact differentiation now but I do recall many folks having problems with log-in credentials for one not working with the other about 20 years ago!
Same happened with Skype after it was bought by Microsoft, and I seem to recall this is relatively recent. There were (are?) two Skype clients - one for 'personal' (the original Skype) and another for 'enterprise' (rebranded Windows Live for Enterprise possibly?) and not compatible. Again, I recall trying to help confused Windows users figure out why the (incorrect) client wouldn't log-in with certain credentials.