The bible teaches us that when somebody is baptized is a good sign of repentance of the person coming back to God. Baptism means giving up your sins and accepting a new life in Christ. At this point you have made up your mind to start living a good life. Baptism is something that is done once in lifetime. Baptism is all about you believing that you're about to have a new change in life and promise to turn away from sinful act.
Ephesians 4:5“One Lord, one faith, one baptism”
Although they are sometimes when someone can be chosen to be baptised for the second time even though is once in a lifetime. A child that was baptized when he was still a baby, at that time he did the baptism without his own decision, when he grows up and decides to accept Christ and come for a baptism with his faith. Then he can be baptized again for the second time. Baptism is not all about accepting to be baptized, but the person being baptized, does he truly believe in what he is about to do. He must be ready to accept Jesus Christ with all his heart.