  We study $N = 2$ 3-d theories with two adjoints and fundamental flavors along
with D-type superpotential. For superpotential $W_{D_{n+2}} = \mathrm{Tr}
\left(X^{n+1}+X Y^2\right)$ with $n$ odd, we propose the 3d dualities, which we
motivate from the dimensional reduction of the related 4-d theory. We consider
the factorization of the superconformal index and match precisely the vortex
partition function of the dual pairs. In the language of the Higgs branch
localization, the nonzero contribution of the vortex partition function comes
from the discrete Higgs vacua of the massively deformed theory, which precisely
matches with that of the dual theory. We also clarify the monopole operators
parametrizing the Coulomb branch of such theories. Existence of independent
monopole operators of charge 2 is crucial to describe the Coulomb branch.
