Weak lensing “post-Born” effects are equivalent to pure lens-lens couplings

We show that the so-called "post-Born" effects of weak lensing at 4th order are equivalent to lens-lens couplings in Born Approximation. demonstrate this by explicitly showing equivalence canonical approach using anisotropy remapping method, calculation coupling Boltzmann equation was first developed [Phys. Rev. D89, 123006]. Furthermore, we argue incorporate true effects, i.e. taking into account non-straight photon paths, require addition a deflection term which has not been taken formalism nor method.