  By taking a product of two sl(2) representations, we obtain the differential
operators preserving some space of polynomials in two variables. This allows us
to construct the representations of osp(2,2) in terms of matrix differential
operators in two variables. The corresponding operators provide the building
blocks for the construction of quasi exactly solvable systems of two and four
equations in two variables. Some generalisations are also sketched. The
peculiar labelling used for the generators allows us to elaborate a nice
deformation of osp(2,2). This gives an appropriate basis for analyzing the
quasi exactly solvable systems of finite difference equations.
