Wow, according to Wikipedia he died of suicide by two to the head. And here I thought stories of suicide via two self-inflicted head shots was a myth restricted to conspiracy theorists.
That said, it looks like the Sacramento coroner does in fact employ at least one forensic pathologist, so that lends a little more credence to the finding. Also, in these high profile cases there are often quite a few witnesses to the autopsy, which makes it more difficult to squash evidence.
And, yes, there are plenty of stories of people surviving a gunshot wound to the head, even remaining conscious.