They had also been baptized, but they had not received the Spirit. In this case, Peter and John had to place their hands on these individuals and pray for them to be born from above by the indwelling Holy Spirit. They were baptized after receiving the Spirit, but there was no laying on of hands. Both these examples teach us that while baptism is an important public statement of our intentions toward God and Christ, it is symbolic. This brings up the matter of the method of baptism.
Different churches baptize in different ways.
If we understand that baptism is primarily a symbolic public statement of our entrance into the community of believers, the church, then we can see that the mode is not critical. The fact of our baptism is the meaningful act. The Worldwide Church of God follows what appears to be the biblical example of baptism by full immersion. When individuals who were once baptized in another church enter the fellowship of the Worldwide Church of God, they sometimes wonder if they should be rebaptized. If they feel they understood what baptism symbolized when originally baptized, and they had committed to Jesus Christ with understanding and faith, then there is no need to be rebaptized.