Leviticus 23:18

Two rams; in Numbers 28:11,19 it is two young bullocks and one ram. Either therefore it was left to their liberty to choose which they would offer, or one of the bullocks there, and one of the rams here, were the peculiar sacrifices of the feast-day, and the other were attendants upon the two loaves, which were the principal and most proper offering at this time. And the one may be mentioned there, and the other here, to teach us that the addition of a new sacrifice did not destroy the former, but both were to be offered, as the extraordinary sacrifices of every feast did not hinder the oblation of the daily sacrifice.