Maybe the question can simply be answered by the observation that a "wave" like $$\Psi(x,t)=\cos(x)+\cos(x+\omega\ t),$$ where the two cosines cancel at times $$t_n=\frac{2\pi}{\omega}n\ \ \longrightarrow\ \ \Psi(x,t_n)=0,$$ still has nonvanishing kinetic energy, if it looks something like $$E=\sum_\mu(\partial_\mu \Psi)^2+\ ...$$ You would really have to construct an example. --- Since non-dissipative waves whose equations of motions can be formulated by a Lagrangian will have an energy associated to them, as you say, you'd have to find a sitation/theory without an energy quantity. So if the energy is defines as that which is constant because of time symmetriy and you don't have such a thing, then there is no question. Also don't make the mistake and talk about about two different waves with different energy. If you have a linear problem, the wave will be "one wave" in the energy expression, whereever its party may wander around.