The Gemara on Amud Aleph discusses the case of two obligatory contracts that seem to be stating the same thing.  Does the second contract abrogate the first, and therefore we follow the dates and commitments in the second contract?  (This would have an impact on liens dated from the first contract, which will now be annulled.) The Gemara concludes that when the contracts are identical, we assume the second one abrogates the first.  However, if the second contract adds any new obligations, even one additional palm tree, we assume that was the purpose of writing the second contract, therefore the other obligations from the first contract remain in place.

The Chida (Simchas Haregel Haggadah Shel Pesach) uses this principle to explain the repeated verse in the Haggadah, “By your blood you shall live, by your blood you shall live.”  The Midrash says that God redeemed the Jews from Egypt on account of the blood of the Passover sacrifice and the blood of Bris Milah.  Each one of them have scriptural sources that indicate God made them as a condition of redemption.  The verse states, “I am your God who took you out of Egypt.” Shemos Rabbah understands this as implying, I took you out of Egypt on the condition that you accept me as your God. This is represented in the blood of the Passover sacrifice, as the Jews renounced the Egyptian Gods at that time by slaughtering their sacred cattle.  

By Bris Milah, Avraham is told (Bereishis 17:7-8):

וַהֲקִמֹתִ֨י אֶת־בְּרִיתִ֜י בֵּינִ֣י וּבֵינֶ֗ךָ וּבֵ֨ין זַרְעֲךָ֧ אַחֲרֶ֛יךָ לְדֹרֹתָ֖ם לִבְרִ֣ית עוֹלָ֑ם לִהְי֤וֹת לְךָ֙ לאלוקים וּֽלְזַרְעֲךָ֖ אַחֲרֶֽיךָ׃

I will maintain My covenant between Me and you, and your offspring to come, as an everlasting covenant throughout the ages, to be God to you and to your offspring to come.

וְנָתַתִּ֣י לְ֠ךָ֠ וּלְזַרְעֲךָ֨ אַחֲרֶ֜יךָ אֵ֣ת ׀ אֶ֣רֶץ מְגֻרֶ֗יךָ אֵ֚ת כׇּל־אֶ֣רֶץ כְּנַ֔עַן לַאֲחֻזַּ֖ת עוֹלָ֑ם וְהָיִ֥יתי לָהֶ֖ם לאלוקים

I assign the land you sojourn in to you and your offspring to come, all the land of Canaan, as an everlasting holding. I will be their God.

These verses imply that the Bris must come first, and then the fulfillment of leaving Egypt and entering the Land of Israel will follow. 

The Chida wonders, are these two conditions (Milah and Pesach) not like two contracts, with the second abrogating the first? He answers that it is more correctly compared to the case where the second contract adds an additional clause, so now both are valid.  The first obligation was to be enslaved for 400 years as was prophesied to Avraham (Bereishis 15:13), and eventually the Jews would go free by the merit of the Bris Milah.  However, the second obligation was to be enslaved for a lesser amount of time, actually 210 years according to tradition (see Rashi Bereishis 21:2), so long as the Jews accepted God via the Paschal sacrifice.

The idea of the Chida can also be understood as relevant to our current state of exile.  The Gemara Sanhedrin 98a states :

אמר רבי אלכסנדרי רבי יהושע בן לוי רמי כתיב (ישעיהו ס, כב) בעתה וכתיב אחישנה זכו אחישנה לא זכו בעתה

Rabbi Alexandri says: Rabbi Yehoshua ben Levi raises a contradiction in a verse addressing God’s commitment to redeem the Jewish people. In the verse: “I the Lord in its time I will hasten it” (Isaiah 60:22), it is written: “In its time,” indicating that there is a designated time for the redemption, and it is written: “I will hasten it,” indicating that there is no set time for the redemption. Rabbi Alexandri explains: If they merit redemption through repentance and good deeds I will hasten the coming of the Messiah. If they do not merit redemption, the coming of the Messiah will be in its designated time.

We see from this that our current exile, like the exile of Egypt, has a two tiered conditional structure.  No matter what, God will eventually redeem us once the (unknown) time limit is reached.  However, we do have the option of meriting a reduced sentence by accepting Hashem as our God by keeping the mitzvos.