Guy, settle down. It's obviously talking about Moira.
First death: When she forsook the Bronzebeards and married Thaurissan.
Second death: When Thaurissan died.
actually, now that I think about it, it might be Maiev.
First death: When Illidaniel died.
Second death: When Illidaniel became Tal'rasha.
or maybe Alexstrasza.
First death: Being the Horde's baby factory.
Second death: When Krasus died.