  This study is performed with the aim of gaining insights into the possible
applicability of the quark-hadron continuity concept, not only in the idealized
case of three-flavor symmetric quark matter, but also for the transition from
neutron matter to two-flavor quark matter. A key issue is the continuity
between neutron superfluidity and a corresponding superfluid quark phase
produced by $d$-quark pairing. Symmetry arguments are developed and relevant
dynamical mechanisms are analyzed. It is pointed out that the $^3P_2$
superfluidity in dense neutron matter has a direct analogue in the $^3P_2$
pairing of $d$-quarks in two-flavor quark matter. This observation supports the
idea that the quark-hadron continuity hypothesis may be valid for such systems.
Possible implications for neutron stars are briefly discussed.
