I don't know, Sion's history seems compatible with Haazen's to me. We know that Haazen was a Jedi who battled the Sith during the time of Exar Kun, so it's very possible that he may have switched sides and joined that particular incarnation of Sith after falling to the dark side.
Haazen's body also looks to me like it could very well have endured what Sion's history describes: reanimation after being struck down by a lightsaber and enduring decomposition. But let's not forget that Sion has also been shattered into tiny pieces, the details of which his back story is silent. This may very well have happened as a result of what we see Haazen endure at the moment of his "death."
But then again, we also know that the writers like to mess with our minds, leading us to believe that certain characters might turn out to be characters from the game, which they often do not (like Krynda). So anything's possible, really.
Originally Posted by a silly noob
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