Am a bit late to this thread but having had a skim through the comments most of them are laughably misguided in terms of the legal rights of the professional photographer over the OP.
Under Australian copyright law, the OP gained sole copyright over the photos that he took as soon as he pressed the shutter. That gives him unfettered rights to commercially exploit his photos.
The only way that the professional could restrict those rights is by virtue of a contract containing explicit terms prohibiting him from using/selling the photos. There is no way that the a court would read in such an onerous term into the very loose arrangement described here. I very much doubt that there is any contract between the OP and the pro photographer governing the shadowing arrangement, but there clearly is no term covering assignment of copyright or prohibition on exploitation of photos.
The one legal claim to the photos of the OP would be from the part of the bride. If we changed the facts a bit here and the OP wanted to sell his photos to a bridal magazine, the bride may be able to restrain this by bringing an action for breach of confidence. However, even this would be a pretty weak action given the reluctance of Australian courts to recognise any tort of privacy. Her only strong action would be against the professional (who she has a contract with) for his negligence in allowing the OP to tag along without requiring him to enter into a contract to restrain his use of the photos. But I digress.
The only issue at stake here is the OP's ethics. And personally I think the professional is the one who should be grateful that the bride isn't tempted to take him to VCAT for stuffing up the coverage: http://newsfeed.time.com/2013/01/13/wedding-photographer-sued-for-missing-the-kiss/
Think a lot of the comments here are fuelled by "professionals" feeling a bit insecure about second shooters
[FWIW I'm in my final year of a law degree]