Does a prayer repeated as a precautionary measure take the place of the first invalid prayer and count as a [fulfilled] obligatory prayer?

Doubt about the validity of an act of worship after completing it has no effect. Re-performing the prayer merely due to doubts is not prescribed, as the Prophet, peace and blessings be upon him, forbade repeating the prayer twice in one day. This action opens the door to obsessive thoughts (waswas), and it is obligatory to close this door. Therefore, repeating the prayer for the aforementioned reason is not legislated. Whoever is not certain that they committed an act that invalidates their prayer, their prayer is valid. It is incumbent upon a Muslim to learn the Sharia rulings to avoid such doubts.