Saying anger does not stack is totally wrong..
I am a 65 War on Mithaniel Marr with BoC:Anger3 in Primary and SobS:Anger3 in secondary slot.. Anger aug effect does stack, They can not proc in same combat round, But NO YOU WILL NOT get a message saying that your spell could not take hold or whatever
I was sadly outrolled on this by just 10. Though afterwards I had enough rep to buy [url=http://wow.allakhazam.com/db/item.html?witem=25836&locale=enUS;source=live]Perservers Cudgel[/url] From the Cenarion Expedition, which is just as good, even if it doesn't look as stunning graphic wise. :(