Zevachim 30B

אמר ליה אביי, והא רבה בר בר חנה אמר רבי יוחנן: כי מגעת להו רבי מאיר ורבי יוסי בהדי הדדי, לא פליגי!

Abaye said to Rav Dimi: But doesn’t Rabba bar bar Ḥana say that R' Yoḥanan says: When you consider their opinions, R' Meir and R' Yosei do not disagree with one another, i.e., neither holds that one attends only to the first statement?

ולא פליגי?! והא מיפלג פליגי! אמר ליה: פליגי במאי דפליגי, ולא פליגי במאי דלא פליגי.

Rav Dimi objected: And is it so that they do not disagree? But don’t they disagree explicitly in the Mishnah cited earlier? Abaye said to him: They disagree where they disagree, i.e., that specific case, but they do not disagree where they do not disagree, i.e., the underlying principle. Accordingly, one must understand the basis of their dispute in another manner.

דאמר רבי יצחק בר יוסף אמר רבי יוחנן: הכל מודים היכא דאמר ״תחול זו ואחר כך (אמר) תחול זו״⁠ – דברי הכל לא חיילא; ״לא תחול זו אלא אם כן חלה זו״⁠ – דברי הכל חיילא;

This is as Rav Yitzḥak bar Yosef says that R' Yoḥanan says: All, i.e., R' Meir and R' Yosei, concede that in a case where one says: Let this sanctity of a burnt offering take effect and afterward let that sanctity of a peace offering take effect, everyone agrees that the sanctity of a peace offering does not take effect, because the sanctity of the burnt offering took effect first. Likewise, if one said: This sanctity should not take effect unless that sanctity applies, everyone agrees that the sanctity of a peace offering takes effect as well.

כי פליגי, דאמר: ״תמורת עולה תמורת שלמים״. רבי מאיר סבר: מדהוה ליה למימר ״תמורת עולה ושלמים״ ואמר ״תמורת עולה תמורת שלמים״⁠ – שמע מינה מיהדר קא הדר ביה.

They disagree with regard to a case where one says: This animal is hereby a substitute for a burnt offering, a substitute for a peace offering. R' Meir holds: Since if he wanted both sanctities to take effect, he should have said: A substitute for a burnt offering and a peace offering, but he said instead: A substitute for a burnt offering, a substitute for a peace offering, learn from his language that he originally intended for it to be a burnt offering, and he then retracted his first intention.