I think this is a wrong information. The twin-brother of Ursol is Ursoc...

hmm.. Edit

well that is what it seems..

and it seems that no one knows who Ursin was, other than that there is a server named after him.

perhaps Ursoc was also known as Ursin?

Discussion on what Ursin is...

http://forums.worldofwarcraft.com/thread.html?topicId=28354656&sid=1

Some posters suggested that it is the language of the Timbermaws