I have just released wp-SwimTeam v.1.5.579, you can find it on the download page and shortly, via the automatic plugin updater. This release fixes an issue which has bothered me personally for a long time.
There was a problem in the E-mail Confirmation code for both registrations and opt-in/opt-out. This same code was used for the new Jobs module so it existed there too. For a long time the confirmation e-mails were duplicated and if a swimmer had to two contacts, only one of them would receive the e-mail. I have finally found and fixed this problem so e-mail confirmation should be cleaner and sent to the appropriate people.