In فَإِنْ لَمْ تَكُنْ تَرَاهُ فَإِنَّهُ يَرَاكَ, the first إِنْ introduces a condition: “if.” The later إِنَّ adds emphasis: “indeed.” These similar-looking particles perform different functions.
تَرَاهُ means “you see Him,” while يَرَاكَ means “He sees you”; the direction of the action has changed.
For example, someone records entrusted money accurately even when alone, mindful that nothing escapes Allah's knowledge. Such awareness encourages sincerity rather than performance for public praise.