@Soul Brother,
Two different objects cannot be identical.
If (Fx and ~Fy) then ~(x=y).
x has the space-time location (a,b,c,d) entails that a different object y does not have the same space-time location (a,b,c,d).
That is, (Fx & ~Fy) is true for the property F ..having the same space-time location, therefore, ~(x=y).
(some F: Fx & ~Fy) => ~(x=y).