  We study the sensitivity of the process $\mu^-\mu^+\to HH$ to the
$q^2$-dependence of the $HHH$ form factor, which can reflect the Higgs boson
structure, especially in the case of compositeness. We compute the Born and 1
loop SM contribution to this process. We then show how the $\mu^-\mu^+\to HH$
polarized and unpolarized cross sections are modified by the presence of
various types of anomalous contributions to the $HHH$ form factor, in
particular Higgs constituents in the case of compositeness.
