Look at how the word ‘iz’ is used 3 times, hence the aid of Allah U came at 3 different times at 3 different situations.
In this verse in Surah Baqarah, the word ‘iz’ is used to refer to a time of success for the children of Israel, so is this simply a repetition or are there secrets in it?
Naturally there are secrets. ‘anjaa’ and ‘najjaa’, both means to save, but there is a difference between their usage. We say, ‘najjaa’ from a punishment that has already occurred as Allah U says here:
﴾إِذْ نَجَّيْنَاكُم مِّنْ آلِ فِرْعَوْنَ﴿
“and when We saved you from the people of Pharaoh” [Surah Al-Baqarah: 49].
In this case the punishment was already occurring. However, in the verse:
﴾وَإِذْ فَرَقْنَا بِكُمُ الْبَحْرَ فَأَنجَيْنَاكُمْ وَأَغْرَقْنَا آلَ فِرْعَوْنَ﴿
“And remember when We parted the sea for you and saved you and drowned the people of Pharaoh” [Surah Al-Baqarah: 50]