  We propose a novel process where singly charged Higgs bosons are produced in
a same-sign pair via vector boson fusion at hadron colliders in two Higgs
doublet models. The process directly relates to the global symmetry structure
of the Higgs potential. The produced charged Higgs bosons predominantly decay
into a tau lepton and the neutrino or into a pair of top and bottom quarks,
depending on the type of Yukawa interactions. We evaluate the signal and the
background for the both cases at the CERN Large Hadron Collider and future
higher-energy hadron colliders. We find that the process can be feasible and
useful to explore the nature of the Higgs potential.
