In here, in the 4th point, we will have to use a counterstain of a different colour, given in example is safranin, but safranin and crystal violet are both for

In here, in the 4th point, we will have to use a counterstain of a different colour, given in example is safranin, but safranin and crystal violet are both for gram -ve bacterias.How will two strains which are for the same gram bacteria can be used to distinguish between them. I am confused with it. Explain in brief please.