  Computation codes in network information theory are designed for the
scenarios where the decoder is not interested in recovering the information
sources themselves, but only a function thereof. K\"orner and Marton showed for
distributed source coding that such function decoding can be achieved more
efficiently than decoding the full information sources. Compute-and-forward has
shown that function decoding, in combination with network coding ideas, is a
useful building block for end-to-end communication. In both cases, good
computation codes are the key component in the coding schemes. In this work, we
expose the fact that good computation codes could undermine the capability of
the codes for recovering the information sources individually, e.g., for the
purpose of multiple access and distributed source coding. Particularly, we
establish duality results between the codes which are good for computation and
the codes which are good for multiple access or distributed compression.
