There was another Biggie Smalls rapper before Christopher Wallace, and that's why he went by the name of Notorious BIG instead of using Biggie Smalls officially.
But, I will say that, Shock G was right, Pac was plottin maybe not on God Bless the Dead, but songs like Killuminati, when he says, I'm certified crazy, so since the world made me, now Biggie died, everytime I ride it's for reasons. Hard to kill a nigga cause I'm comin back like Jesus.
I don't believe that's an alive theory, i just think Pac was that deep into making himself live forever in the hearts of his enemies, foes and keep fighting them from the grave (hence make himself a threat, dead or alive).