  We perform a calculation of the $\tau^- \to \nu_{\tau} M_1 M_2$, with $M_1,
M_2$ either pseudoscalar or vector mesons using the basic weak interaction and
angular momentum algebra to relate the different processes. The formalism also
leads to a different interpretation of the role played by $G$-parity in these
decays. We also observe that, while $p$-wave $M_1 M_2$ production is compatible
with chiral perturbation theory and experiment, $VP$ and $VV$ $p$-wave
production is clearly incompatible with experiment and we develop the formalism
also in this case. We compare our results with experiment and make predictions
for unmeasured decays, and we show the value of these reactions, particularly
if the $M_1 M_2$ mass distribution is measured, as a tool to learn about the
meson-meson interaction and the nature of some resonances, coupling to two
mesons, which are produced in such decays.
