Some of them may ask: “Why this repetition?” The purpose of the statements is basically different. The verse No. 52, said:
( كَفَرُوا بِآيَاتِ اللَّهِ ) (They disbelieved in the signs of Allah,): thus, the cause of the punishment is the disbelief. Whereas here, it says:
(كَذَّبُوا بِآيَاتِ رَبِّهِمْ) (They denied the signs of their Lord,): Indicating that they knew the signs but denied them, refusing to acknowledge the favors of Allah. Thus, they are being reproached for their ingratitude for the favors of Allah.
( آلَ فِرْعَوْنَ ۚ وَكُلٌّ كَانُوا ظَالِمِينَ فَأَهْلَكْنَاهُم بِذُنُوبِهِمْ وَأَغْرَقْنَا ) (So, We destroyed them because of their sins, and We drowned the people of Pharaoh.): The text here clearly indicates the punishment, which is the drowning that occurred to Pharaoh and his people.
(وَكُلٌّ كَانُوا ظَالِمِينَ) (And all [of them] were wrongdoers.): Hence, this verse talks about the denial of faith and disbelief as Pharoah had done. The verse before was regarding the blessings that Allah (swt) had bestowed upon them but they had denied them. Therefore, there is no repetition between the two verses but instead there are secrets that can be derived.