  Measurements by the Belle Collaboration of the exclusive production of two
charmonia in e^+ e^- annihilation differ substantially from theoretical
predictions. Till now, no conclusive explanation for this remarkable
discrepancy has been provided. Even the origin of the discrepancy is not
identified, yet. We suggest that the measurement of four-charm events in Belle
data must provide a strong constraint in identifying the origin of this large
discrepancy. Our prediction of the cross section for e^+e^- -> c c-bar c c-bar,
in lowest order in strong coupling constant, at sqrt{s}=10.6 GeV is about 0.1
pb. If measured four-charm cross section is compatible with the prediction
based on perturbative QCD, it is very likely that factorization of
hadronization process from perturbative part may be significantly violated or
there exists a new production mechanism. If the cross section for the
four-charm event is also larger than the prediction like that for the exclusive
J/psi+eta_c production, perturbative QCD expansion itself will be proved to be
unreliable and loses predictive power.
