I was baptized twice as a JW. The first time I was 7 years old, this was too young for me to know what I was getting into. The second time I was 28, this time I was too dumb to know what I was doing, so neither time worked.
There are a lot of religions besides the JW's who do not baptize infants; Baptists, Seventh-day Adventists, various Pentecostal and Church of God groups, Church of Christ, all baptize as adults, not babies. Even Mormons wait until the child is 8 years old.
Personally, I've only been baptized once, by the JW's. I know what it meant to me, and it didn't mean joining an organization. I feel no need at this point to be rebaptized.
I was baptized @ 13 by the JW's - because I wanted to look good and get a guy who was cute. I also really believed it was the "truth".
I was baptized again 2 yrs ago by a non-denominational church because I became a born again Christian. The 2nd baptism meant a lot more to me - it meant that I was free, and that I wanted to have Jesus in my life.