  We consider an out-of-equilibrium one-dimensional model for two electrical
double-layers. With a combination of exact calculations and Brownian Dynamics
simulations, we compute the relaxation time ($\tau$) for an electroneutral
salt-free suspension, made up of two fixed colloids, with $N$ neutralizing
mobile counterions. For $N$ odd, the two double-layers never decouple,
irrespective of their separation $L$; this is the regime of like-charge
attraction, where $\tau$ exhibits a diffusive scaling in $L^2$ for large $L$.
On the other hand, for even $N$, $L$ no longer is the relevant length scale for
setting the relaxation time; this role is played by the Bjerrum length. This
leads to distinctly different dynamics: for $N$ even, thermal effects are
detrimental to relaxation, increasing $\tau$, while they accelerate relaxation
for $N$ odd. Finally, we also show that the mean-field theory is recovered for
large $N$ and moreover, that it remains an operational treatment down to
relatively small values of $N$ ($N>3$).
