What if I have been baptized twice?
The Bible teaches that baptism must not and does not need to be renewed. Once it is delivered it is always valid. This fact does not change if we reject God after our baptism. We may always return to our Father, He is waiting for us. And when we come back, we do not need a new baptism.
However, there are those who want to be baptized again or have already been baptized again. And there are those who baptize people again. Many of those might think that if a person is baptized as a child, it is not a real baptism. That is a serious claim. That would mean that you are not baptized and hence not a Christian. Some people say that if a person, at the moment of baptism, does not understand that he/she is baptized, then it can not be a real baptism. But baptism is an act of God and an act of God does not depend upon how much a person understands. We did not understand what happened when Jesus died on the cross for us - we didn’t even exist when it happened. But it was still an act of God and our salvation.
Thus, the baptism should not be renewed. A person who has taken a second baptism has done wrong. Whoever has done wrong, has the opportunity to confess the deeds to God and to ask for His forgiveness. And God forgives those who repent and believe that Jesus has reconciled all the sins of all people.
one Lord, one faith, one baptism
(Ephesians 4:5, ESV)