Forum Moderators: not2easy
If you can prove that you created it first, then you don't actually have to register copyright or display a copyright notice on a work to be protected. Registering just makes it a whole lot easier to prove.
If you want to pursue this legally, get a lawyer who specializes in intilectual property law.
If you applied "sweat of the brow" and some creative effort to make the collection, then you have protection under copyright, either by express statutory provision (i.e. in the UK, it is the CDPA 1988 provision on "typographical arrangement"), or through case law (I belive this to be the US situation?). You are protected in all countries that are signatories to the Berne convention or the WTO TRIPs agreement (which implies agreement to Berne). The fact that someone has taken your exact code suggests that they are directly infringing your copyright, and that would be very easy to prove (in copyright infringement, you actually need prove copying, not just that they are the "same", as copyright protects expression, not idea).
If your content is hosted in the EU, then you would have additional "sui generis" protection as a database under the database directive as implemented by EU member states. This is a separate right to copyright, and protects databases irrespective of the creativity applied: the intention is to protect the investment involved in putting the material into the database, and maintaining the database. As a side note, this is one beneficial reason for hosting in the EU if you have particular content on your system. This is an EU only right.
If you have copyright notices, then these help illustrate that copying has taken place, and help with the extent of remedies (e.g. prima facie evidence to request interim injunction [cease and desist?], or damages and final remedies). The UK CDPA 1988 has express provisions indicating this. It's always good practivce to put these notices.
The issue you have is that should you claim infringement, you may need to prove who is the original creator of the work as the other party could counterclaim that you infact stole it from them. So how can you prove this? This is one beneficial reason for registration, but I also wonder about whether people will use digital notarisation systems for this purpose (e.g. every update of your website, you notarise a snapshot that can be used as evidential proof of owernship and a history of development). The web archive and search engine archives may be useful to establish whose content came first.
Even then, what can you do? Take the person to court? I'm not sure how legal process for this works, and how you deal with international issues (there are various agreements to allow countries to directly serve notices on others : brussels and lugaro agreements e.g.).
Matthew.