Manifestation of $\mathrm{Co}∕\mathrm{Mn}$ ordering on the spin-lattice dynamics of ${\mathrm{La}}_{2}\mathrm{Co}\mathrm{Mn}{\mathrm{O}}_{6}$ (LCMO) double perovskites is studied by Raman spectroscopy. We investigate the temperature dependence of the magnetic and the optical properties for (i) microcrystals containing both the ordered and disordered phases and (ii) $\mathrm{Co}∕\mathrm{Mn}$ ordered epitaxial films. Our results show distinct onsets of phonon mode softening in the vicinity of the magnetic phase transitions, revealing a strong spin-lattice coupling in LCMO. Moreover, $\mathrm{Co}∕\mathrm{Mn}$ ordering in the thin films leads to the appearance of additional excitations that had not been observed previously. We interpret these features as a result of Brillouin zone folding due to the doubling of the unit cell in the ordered phase.