Much is written about the relationship of Shamor and Zachor in relation to Shabbat but Shamor and Zachor are also used for Pesach (at least the first day) - Shmot 13:3
Moses said to the people, "Remember this day, when you went out of Egypt, out of the house of bondage, for with a mighty hand, the Lord took you out of here, and [therefore] no leaven shall be eaten.
וַיֹּאמֶר משֶׁה אֶל הָעָם זָכוֹר אֶת הַיּוֹם
הַזֶּה אֲשֶׁר יְצָאתֶם מִמִּצְרַיִם מִבֵּית עֲבָדִים כִּי בְּחֹזֶק יָד הוֹצִיא יְהֹוָה אֶתְכֶם מִזֶּה וְלֹא יֵאָכֵל חָמֵץ
You shall observe the festival of unleavened bread; for seven days you shall eat unleavened bread as I have commanded you, at the appointed time of the month of springtime, for then you left Egypt, and they shall not appear before Me empty handed.
.אֶת חַג הַמַּצּוֹת תִּשְׁמֹר שִׁבְעַת יָמִים תֹּאכַל מַצּוֹת כַּאֲשֶׁר צִוִּיתִךָ לְמוֹעֵד חֹדֶשׁ הָאָבִיב כִּי בוֹ יָצָאתָ מִמִּצְרָיִם וְלֹא יֵרָאוּ פָנַי רֵיקָם:
While in terms of Pesach, the word "kadosh" is missing, I was wondering if there was something special about Pesach that it deserves the same doubled language as Shabbat (or if, lacking "l'kadsho" removes any special status to the use of the 2 words). Or is the special status of the two words because they were both said bdibbur echad?
Does the use of both terms, Shamor and Zachor, bring any new understanding to how we observe Pesach as compared both to Shabbat and other holidays about which both words aren't used?