Hello,
I don't know if this was already addressed, but I was recently working with http sessions and it appears that when this extension is active, two instances of any variable get saved. For example, if I have a list as a session object and I try to add an item X to that list, two instances of X will be present in the list. Even if I have a simple integer variable and perform any operation on it (say, an addition) it will be performed twice. I hope I got the point across. I've got the last version of the extension and all and I'm definately sure it's the cause of this behavior.