Adding yeast when bottling lager?

[Mullett]

Have been brewing some k&k lagers using 34/70 yeast, the recipe says to add another yeast packet at bottling time - I guess to help with carbonation. Is this really necessary? In previous brews I've fermented for 2weeks, increased temp for diacetyl rest then slowly dropped the temp to 2C for a month prior to bulk priming adding yeast then bottling. its worked well each time but if leaving out the second yeast addition didn't change the final product it'd save a few $$