OK, so I was in the middle of a discussion in the Templar WW channel about the Hateshield proc, and whether or not you can have two on one person or not, so I decided to do some testing.
I joined a group with our MT Defiler, and had him cast crap on me while I was casting shit on myself.
Well, for the non-believers, here's a screenshot, with the 2 Hateshield procs in my beneficial spells bar circled in red. One from me, one from the Defiler. This is also from today, 12-18-2008. Discuss!!

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Good evening Sir, my name is Fenuxx. I come from a rough area.
I used to be addicted to crack but now I am off it and trying to stay clean.
That is why I am selling magazine subscriptions.
Fenuxx - 80 Templar
Diio - 80 Shadowknight
Iommi - 80 Dirge
Rathalos - 80 Guardian