2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/185720A necessary condition that a Stäckel-Killing tensor of valence 2 be the contracted product of a Killing-Yano tensor of valence 2 with itself is re-derived for a Riemannian manifold. This condition is applied to the generalized Euclidean Taub-NUT metrics which admit a Kepler type symmetry. It is shown that in general the Stäckel-Killing tensors involved in the Runge-Lenz vector cannot be expressed as a product of Killing-Yano tensors. The only exception is the original Taub-NUT metric.14 pages, LaTeX. Final version to appear in J.Phys.A:Math.GenHigh Energy Physics - TheoryGeneral Relativity and Quantum Cosmologytext