There is no such thing as being baptized twice. Someone does not need to be baptized twice. When you have been baptized, with the right baptism, you do not need to be baptized again. The apostles in the Bible were not baptized twice. Our Lord Jesus Christ was not baptized twice. So, we do not in anyway need another baptism after we have been baptized before.
Baptism is to follow genuine repentance. Someone can only be baptized after he has accepted the doctrines of Jesus Christ and repented of his sins. Someone who continues in sin and get baptized is only having a bath in the water. Jesus Christ only commanded that he that believes should be baptized.
In the religious setting, many people go and get baptized just because they want to fulfill a religious rite. Such a type of baptism is a false one. True baptism is the one that is done to someone who has surrendered his life to Jesus Christ.
When a person has come to hear the truth and accepted the doctrines of Jesus Christ. If he accepts to turn away from every sin, that person can come and be baptized. If he has been baptized before that time, that first baptism is not right.