  In this talk we review the work in [1,2,3] where we have studied the
applicability of the color-kinematics duality to the scattering of two
distinguishable scalar matter particles with one gluon emission in QCD, or one
graviton emission in Einstein gravity. We have shown that the duality works
well in the Regge limit under two different extensions of the gauge theory: the
introduction of a new scalar contact interaction and the relaxation of the
distinguishability of the scalars. Both modifications correspond to theories
obtained by dimensional reduction from higher-dimensional pure gauge theories.
