The Chizkuni wrote the following: "It is a night of 'Shimurim' for Hashem"—because He protected them from the destroyer when He struck Egypt. Therefore, the Holy One, Blessed Be He, commanded that it should also be a night of 'Shimurim' for Israel for all generations, that they should guard that night, not sleep, but rather give thanks and recount the miracles and mighty deeds that Hashem performed for us on that night. 'Shimurim'—garde in Old French. Another explanation: a night of 'Shimurim'—that they should guard to eat their Pesachs on it, as an example: 'You shall guard to offer to Me in its appointed time' (Numbers 28:2)." End of quote.

So, his interpretation of the first 'Shimurim' aligns with that of Ibn Ezra, where its use is in the simple meaning of protection from harm. Regarding the second 'Shimurim'—Chizkuni's first interpretation is as some commentators brought by Ibn Ezra, and as we have already stated, according to this, this 'Shimurim' serves two meanings: the first is a language of caution, that Israel needs to be cautious on this night to observe it by fulfilling its commandments. The second is a language of uniqueness and designation, that this night is unique and designated for giving thanks and recounting the mighty deeds of Hashem when they left Egypt. Chizkuni's second interpretation follows Ramban's approach, where this second 'Shimurim' refers to the commandments of the night and its use is in the language of caution regarding its observance.