  Linear operators preserving the direct sum of polynomial rings P(m)\oplus
P(n) are constructed. In the case |m-n|=1 they correspond to atypical
representations of the superalgebra osp(2,2). For |m-n|=2 the generic, finite
dimensional representations of the superalgebra q(2) are recovered. An example
of a Hamiltonian possessing such a hidden algebra is analyzed.
