Tagged kaon beams are attractive neutrino sources, which would provide flavor pure $��_e$-beams with exactly measured normalization. We point out that this also leads to an anti-tagged flavor pure $��_��$-beam, with equally well known normalization. Exposing a 1 kt liquid argon detector at a baseline of 1 km to this combination of unique beams allows to decisively test recent indications by IceCube and Neutrino-4 of sterile neutrino oscillations in the multi-eV range.

5 pages, 3 figures