  We consider quantum models corresponding to superymmetrizations of the
two-dimensional harmonic oscillator based on worldline $d=1$ realizations of
the supergroup SU$(\,{\cal N}/2\,|1)$, where the number of supersymmetries
${\cal N}$ is arbitrary even number. Constructed models possess the hidden
supersymmetry SU$(\,{\cal N}/2\,|2)$. Degeneracies of energy levels are spanned
by representations of the hidden supersymmetry group.
