In my opinion...No.. You've got to take the time of year into account. The Wiking figures are dressed in their regular temperate uniforms, and in warmer weather (The Kovel Encirclement happened during spring/early summer, these guys look like they're dressed in early Spring, 44, hence the gloves and neck toques), the 20th Waffen-SS kit has the Panzer Grenadiers in reversible winter uniforms, placing them in the winter of 44...
Have you bought them already and trying to use them together on a dio?