Dichotomous key can’t decide? Something is happening to the coloration of the flowers of this Veronica spp.

When I arrive to the genus Veronica my dichotomous key tells me to find EITHER blue flowers OR white flowers to decide between Veronica polita OR Veronica cymbalaria. I can't find any info on wether either of them can exceptionally have white or blue flowers. What do I do when that happens? Why is this plant showing both? Why is pigment lacking? If it helps, only terminal flowers seem to grow either blue or white.