I just took a closer look and by viewing the source of the rendered page there is a link there with no text so it was not visible in the browser but does exist.
<a href="Register.aspx" id="ctl00_mainContent_LoginCtrl_lnkRegister"></a>
It seems there is an extra link besides the one I showed the hide logic for. My best guess is its just a relic from the old implementation before 2.0 .NET came out and provided a LoginControl we had implemented our own. I think this link can be safely removed from the Logoin.aspx file using a text editor, look for this and remove it:
<br /><a id="lnkRegister" href="Register.aspx" runat="server"></a>
I just removed it from my copy and it seems fine.
Hope it helps,