What is the ruling on someone who prays two Friday prayers on the same day?

It is not permissible to repeat a fard (obligatory) prayer except for a legitimate Shar'i reason, such as attending a congregational prayer after having prayed individually, due to the Prophet's (PBUH) saying: "Do not pray a prayer twice in one day." It is disliked to intentionally repeat a prayer without a reason. The validity of repeating a prayer in front of the Imam differs according to the schools of thought; some invalidate it absolutely, while others validate it with dislike or with the condition of an excuse. If you prayed in front of the Imam without an excuse, then repeating it is correct. However, if you believe the first prayer was valid, then it should not be repeated except with the intention of a voluntary prayer.