  We consider the nonlinear wave equation known as the $\phi^{6}$ model in
dimension 1+1. We describe the long time behavior of all the solutions of this
model close to a sum of two kinks with energy slightly larger than twice the
minimum energy of non constant stationary solutions. We prove orbital stability
of two moving kinks. We show for low energy excess $\epsilon$ that these
solutions can be described for long time less o equivalent than
$-\ln{(\epsilon)}\epsilon^{-\frac{1}{2}}$ as the sum of two moving kinks such
that each kink's center is close to an explicit function which is a solution of
an ordinary differential system. We give an optimal estimate in the energy norm
of the remainder $(g(t),\partial_{t}g(t))$ and we prove that this estimate is
achieved during a finite instant $t=T\lesssim
-\ln{(\epsilon)}\epsilon^{-\frac{1}{2}}.$
