Clicking on multiple anchor links while in overlay causes a page refresh potentially causing form data to be lost

This bug report comes from the work I've been doing here: #1493324: Inline form errors for accessibility and UX

Steps to reproduce

1. Visit a page with at least 2 anchor links on it (ex. <a href="#achor">) that opens in the overlay. The attached FOO module creates a page at admin/foo for you.
2. Use firebug (or whatever) to make a visible change to the markup on the page (just so you can see that it goes away later)
3. Click one of the anchor links and note that all is well
4. Now click another link (or the same link again)
5. Notice that the page refreshes (as proof, the change you made with firebug is gone).

This is particularly bad on pages that have forms as any data the user has entered is now gone.

Expected behavior

When I click on an anchor link - no matter how many of them and no matter how many times I click - the page should simply move within the browser view and should not refresh.