The latest measurement of the KS→γγ branching ratio clearly shows an enhancement over the current theoretical prediction. As in other K and B meson decays, this invites to consider the possibility of the contribution of new physics. We study a particular form of the latter, which may be refered to as manifest mirror symmetry. The experimental data are described using previously determined values for the mixing angles of the admixtures of mirror matter in ordinary hadrons and by assuming that for π0, η, η′ → γγ, the mirror decay amplitudes have the same magnitudes as their ordinary counterparts.