Ibn Ezra on Leviticus 23:12

והמכחישים אמרו כי בן שנה איננו כבן שנתו כי בן שנתו עוד אין לו שנה ובן שנה שיש לו שנה תמימה והנה לא קראו בחנוכת המזבח כבש אחד בן שנתו לעולה ובפרשה אחרונה כבשים בני שנה שנים עשר: Those who deny the Rabbinic tradition¹⁵⁶The Karaites. say that ben shanah (of the first year) (Ex. 12:5) does not have the same meaning as ben shenato¹⁵⁷Literally, of his first year. (of the first year), for ben shanato refers to a lamb under a year and ben shanah refers to a lamb of a complete year. Note, they did not read the section dealing with the dedication of the altar. The latter reads, one he-lamb of the first year (ben shenato), for a burnt offering (Num. 7:15). However, in the final section¹⁵⁸Which summarizes the number of sacrifices offered when the altar was dedicated. it reads, the he-lambs of the first year (bene shanah) twelve (Num. 7:87).¹⁵⁹We thus see that Scripture refers to the same lamb by either phrase. There is thus no difference between them; they mean the same.