Why does the Torah see fit to insert "Mil'vad Shabbsos Hashem" in the Parshah of Musfei Yom-Tov?
Sifra: To teach us that on the Shabbos that falls during Yom-Tov, one is obligated to bring the Musaf of Shabbos independently, and not to be Yotzei with the Musaf of Yom-Tov. 1
See Torah Temmah, note 114.
What is "Mil'vad Matnoseichem" coming to include?
Yerushalmi Rosh Hashanah, 1:1): It includes the Korb'nos Yachid and Korb'nos Tzibur 1 that one is Makdish on Yom-Tov in honor of Yom-Tov. 2
Presumably, this refers to Olas Kayitz ha;Mizbe'ach, since the Tzibur cannot bring Shelamim as a Nedavah, and presumably, bearing in mind the principle 'Ein Mevi'in Nedarim u'Nedavos be'Yom-Tov', both the Korb'nos Yachid and the Korb'nos Tzibur are referring to Chol ha'Mo'ed.
As the Torah writes in Re'ei Devarim, 16:17 "Ish ke'Matnas Yado". See also Torah Temimah, note 115.
Why does the Torah insert the (otherwise superfluous) words "asher Titnu la'Hashem"?