  We address the question of whether the upcoming generation of dark matter
search experiments and colliders will be able to discover if the dark matter in
the Universe has two components of weakly interacting massive particles
(WIMPs). We outline a model-independent approach, and we study the specific
cases of (1) direct detection with low-background 1 ton noble-gas detectors and
(2) a 0.5 TeV center of mass energy electron-positron linear collider. We also
analyze the case of indirect detection via two gamma-ray lines, which would
provide a verification of such a discovery, although multiple gamma-ray lines
can in principle originate from the annihilation of a single dark matter
particle. For each search "channel", we outline a few assumptions to relate the
very small set of parameters we consider (defining the masses of the two WIMPs
and their relative abundance in the overall dark matter density) with the
relevant detection rates. We then draw general conclusions on which corners of
a generic dual-component dark matter scenario can be explored with current and
next generation experiments. We find that in all channels the ideal setup is
one where the relative mass splitting between the two WIMP species is of order
1, and where the two dark matter components contribute in a ratio close to 1:1
to the overall dark matter content of the Universe. Interestingly, in the case
of direct detection, future experiments might detect multiple states even if
only ~ 10% of the energy-density of dark matter in the Universe is in the
subdominant species.
