This is straight from the explaination of Aura's in the New Player Guide section (I'd post the link to it but the servers are currently swamped because game servers are STILL offline.)
Note: In rare cases, some items also provide aura effects that are not unique. The damage caused by a Sunfire Cape, for instance, increases with each instance of the item a champion equips.
This is just one example of many delayed changes I see happen between actual game changes and updates to the website, so I figured I would point it out to help Riot out a tad.
I know you guys are probably very busy so little details like this probably slip all the time, doing my part to make the website better. ^^
© 2013 Riot Games, Inc. All rights reserved. Riot Games, League of Legends and PvP.net are trademarks, services marks, or registered trademarks of Riot Games, Inc.