  We study the interplay of particle-hole symmetry and fermion-vortex duality
in multicomponent half-filled Landau levels, such as quantum Hall gallium
arsenide bilayers and graphene. For the $\nu{=}1/2{+}1/2$ bilayer, we show that
particle-hole-symmetric interlayer Cooper pairing of composite fermions leads
to precisely the same phase as the electron exciton condensate realized in
experiments. This equivalence is easily understood by applying the recent Dirac
fermion formulation of $\nu{=}1/2$ to two components. It can also be described
by Halperin-Lee-Read composite fermions undergoing interlayer $p_x{+}ip_y$
pairing. An RG analysis showing strong instability to interlayer pairing at
large separation $d\rightarrow \infty$ demonstrates that two
initially-decoupled composite Fermi liquids can be smoothly tuned into the
conventional bilayer exciton condensate without encountering a phase
transition. We also discuss multicomponent systems relevant to graphene, derive
related phases including a $Z_2$ gauge theory with spin-half visons, and argue
for symmetry-enforced gaplessness under full SU$(N_f)$ flavor symmetry when the
number of components $N_f$ is even.
