Whom to believe?

Consider these two explanations for this result, energy stored in a capacitor = 12CV² !

Explanation 1:

Suppose the plates of capacitor of surface area A and charged with charges +Q and -Q are almost in contact. Now, the plates are moved to a separation of x. Let the plate with +Q be P₁ and the other be P₂.

Now, force on P₁ by P₂ = Q²2Aε_°

Therefore work done in increasing separation from 0 to x = Fd = Q²x2Aε_°=Q²2C where C is the new capacitance of the system.

Using Q=CV,

Energy = 12CV²

Explanation 2:

Let the field existing between the two plates be E.

Now, the plate P₁ is pulled away from P₂ and the separation is increased to x from 0.

Force acting on the plate P₁ = 12QE

Half because the charges on the surface of the plate last over a few atomic layers and hence some of the charges are actually inside the conductor where field is zero.

Hence, average force = 0+QE2

Now work done = Fd = 0+QE2.x = 12Q(E.x)=12QV where V is the potential difference between the plates.

Now, using Q=CV, Energy of the system = 12CV²

-------------------------------------------

Now, doubt arises because of the way the two explanations exploit the electric field. One explanation says force acts because of the field due to charge distribution on the other plate while the other uses the net field of the system which includes the field due to the charge distribution of the plate being moved too. So, which one is wrong or are they both correct? Big problem is the explanations are not mine, and come from two trusted sources, where probability of being wrong goes down exponentially! [3]