Anchor links pasted are being changed

Having an issue with CKEditor (3.3.1) that is a very annoying, pesky thing:

Clients using our system sometimes will use anchor links within a single page. Top of the content is a list of links to anchors later in the page, and then after each of those areas, they have a 'back to top' link referencing an anchor at the top of the aforementioned list.

The issue comes when the client is adding to the list of items. Generally they're plugging in the content below, adding an anchor above it, going back up to the top of the page and adding a link referencing that anchor. As those are all new anchors/links, they're going through the normal process of building those.

The trick is that they're copying/pasting the "Back to Top" link from another item to use for the new item. And CKEditor is regurgitating the link in this case - it's going from

<a href="#anchor">Back to Top</a>

to

<a href="http://my.domain.com/this/is/the/current/page#anchor">Back to Top</a>

Whatever the page URL is that contains the editor in use, that URL is being tacked onto the front of the original, legit href value. And in my case, it's a link to our client-only CMS - which outside folks (who would be clicking this link) have no access to.

For the short term, I'm going to add some code to my processing script to remove these bits when they pop up - but that's a band-aid. CKEditor really shouldn't be doing this to start with.