This pertains to the HTML5 localStorage functionality, as outlined here:
From the localStorage specification (http://dev.w3.org/html5/webstorage/#localStorageEvent):
"When the setItem(), removeItem(), and clear() methods are called on a Storage object x that is associated with a local storage area, if the methods did something, then for every Document object whose Window object's localStorage attribute's Storage object is associated with the same storage area, other than x, send a storage notification."
This means that a storage event should be fired in every window/tab EXCEPT the one that updated the localStorage object which caused the event.
The correct behavior is happening in Firefox (17), Chrome (23) and Safari (5.1.7), however IE9 and IE10 both incorrectly fire the storage event in ALL windows/tabs, specifically the one that originated the change.
This has been discussed on StackOverflow here: