I'm not surprised this worked for you (altho it won't work in every case). Despite the paranoia surrounding KH "records" the fact is that JWs are notoriously lousy record-keepers. This is because the record-keeping at the KH is relegated to the Secretary, and in most congos the Secretary position is the most despised of all ... no elder wants the job because it is so damn much work. As a result, the appointment usually goes to the newest elder, who shortly thereafter starts looking for a way to get out of it. It is amazing how often the Secretary in a congo is the guy who can't spell, can't construct a letter, can't balance his own checkbook, and whose filing system is a series of piles of paper on top of his desk (if he has a desk).
The date of baptism goes on a space on your personal publisher record card. This is supposed to be filled in shortly after your baptism -- although as a former Secretary (not for long) I received cards in the mail for move-ins that did not have the baptism date on them and had to ask the publisher for the information so I could update the card.
If someone has moved a few times, the only record the congo has of your baptism is this date on the card (and sometimes those dates are wrong or estimates). If you insist this was entered without your knowledge and is in error, who can dispute it?
My only question is whether names of baptized persons are sent in by the CO when he visits every six months. I can't recall, but I don't think so... I believe just the number of newly baptized ones is recorded. Does anyone remember if the WTS gets these names?