Why does the Torah mention specifically the "two lambs of the Shelamim"?
Rashi (on Pasuk 20): To preclude the bull and the rams from the Tenufah
(which is performed whilst the lambs are still alive).
Rashi (in Pesachim, 13b): It is the Shechitah of the two lambs which sanctifies the Sh'tei ha'Lechem and which permit the Kohanim to eat them.
Rashi (in Sukah, 37b): The Kohen places the two loaves on the lambs and waves them.
How do we know that this is not synonymous with the Korban Musaf which the Torah discusses in Pinchas?
Rashi: Because the two bulls and one ram mentioned here does not tally with the one bull and two rams mentioned there.
In any event it would be difficult to say that the Torah here is presenting the Korban Musaf, as why would the Torah repeat it here