Shalom Rav,

At first I thought that, according to Rav Ashi, the Torah needs to add the second "Ad Boker" because otherwise we would have thought that the Aseh of burning the Nosar applies even on Yom Tov, and we would learn from here that Aseh Docheh Lo Sa'aseh v'Aseh.

Then I saw the Torah Temimah who, citing the Mechilta, explains that the second "Ad Boker" comes to teach us that "Boker" here means not until midday (according to the Chachamim) or four hours (according to Rebbi Yehudah) as "Boker" usually means, but ha'Netz ha'Chamah (and he cites the Gemara in Pesachim which makes a similar Derashah with regard to the Ketores preceding the Tamid). Incidentally, this latter answer will apply to the same question that you could have asked on Abaye and Rava as well.

Wishing you a Chag Kasher v'Same'ach, and that you and yours remain healthy.

B'Virchas Kol Tuv,

Eliezer Chrysler