  The possibility for a two-channel Kondo ($2CK$) non Fermi liquid state to
appear in a metal as a result of the interaction between electrons and movable
structural defects is revisited. As usual, the defect is modeled by a heavy
particle moving in an almost symmetric double-well potential (DWP). Taking into
account only the two lowest states in DWP is known to lead to a Kondo-like
Hamiltonian with rather low Kondo temperature, $T_K$. We prove that, in
contrast to previous believes, the contribution of higher excited states in DWP
does not enhance $T_K$. On the contrary, $T_K$ is reduced by three orders of
magnitude as compared with the two-level model: the prefactor in $T_K$ is
determined by the spacing between the second and the third levels in DWP rather
than by the electron Fermi energy. Moreover, $T_K$, turns out to be
parametrically smaller than the splitting between the two lowest levels.
Therefore, there is no microscopic model of movable defects which may justify
non-Fermi liquid $2CK$ phenomenology.
