  In [3], the authors showed the existence and the uniqueness of a
sl(m+1,\R)-equivariant quantization in the non-critical situations. The curved
generalization of the sl(m+1,\R)-equivariant quantization is the natural and
projectively equivariant quantization. In [1] and [7], the existence of such a
quantization was proved in two different ways. In this paper, we show that this
quantization is not unique.
