  This paper concerns some spectral properties of the scalar dynamical system
defined by a linear delay-differential equation with two positive delays. More
precisely, the existing links between the delays and the maximal multiplicity
of the characteristic roots are explored, as well as the dominancy of such
roots compared with the spectrum localization. As a by-product of the analysis,
the pole placement issue is revisited with more emphasis on the role of the
delays as control parameters in defining a partial pole placement guaranteeing
the closed-loop stability with an appropriate decay rate of the corresponding
dynamical system.
