Krsna is one. He can expand Himself in many forms. That is different thing. But Krsna... Advaitam acyutam anadim ananta-rupam [Bs. 5.33]. Ananta haya. He has multi, innumerable forms, but still, He's one, advaita. Advaitam acyutam, He does not fall. Suppose isvarah sarva-bhutanam hrd-dese 'rjuna tisthati [Bg. 18.61], because Krsna has expanded Himself in many millions of forms to stay within the heart of the living being, that does not mean Krsna has fallen. Avyayatma. He's the same Krsna. There is no difference.
Lecture on Bhagavad-gita 4.6, Bombay, March 26, 1974