JOEL - You already answered your own question. God was giving the same revelation to both men, because both of them were called to do the same thing. Giving each one their own revelation would impress upon their minds the importance of their roles as witnessses to the Book of Mormon.
Joseph Smith felt that every revelation pertaining to the restoration of the church was very important, because each one came from God. Therefore he was very careful to preserve and publish every single one of them even if the revelations seemed to repeat the same things.