Son of a former Baptist minister here who grew up in the church. In Evangelical circles like the ones you are describing it is not common for adults to be re-baptized, not so long as they were originally baptized after their "born again" experience.

Evangelicals are often baptized as children, anyway. From as young as 8 or 10 years old, depending on when they believe the "age of accountability" begins, after which the child needs to "be saved." Then baptized.

"Once saved always saved" implies once baptized always baptized, so it's very rare to see people baptized more than once. It's not theologically sound according to most Evangelical Protestants.

Things get a little more complicated in mainline Protestant denominations, where baptism can be more of a formal gesture of publicly joining the church. It sounds like the mega church where you were baptized for the second time had been influenced by that kind of thinking, mixed in with some showmanship and PR.