  Axions are likely to be the Dark Matter (DM) that cosmological data require.
They arise in the Peccei Quinn solution of the strong CP problem. In a previous
work we showed that their model has a simple and natural generalization which
yields also Dark Energy (DE), in fair proportions, without tuning any
parameter: DM and DE arise from a single scalar field and are weakly coupled in
the present era. In this paper we extend the analysis of this dual-axion
cosmology and fit it to WMAP data, by using a Markov chain technique. We find
that LCDM, dynamical DE with a SUGRA potential, DE with a SUGRA potential and a
constant DE-DM coupling, as well as the dual-axion model with a SUGRA
potential, fit data with a similar accuracy. The best-fit parameters are
however fairly different, although consistency is mostly recovered at the
2-sigma level. A peculiarity of the dual-axion model with SUGRA potential is to
cause more stringent constraints on most parameters and to favor high values of
the Hubble parameter.
