WP Visual Editor bug?

I’ve discovered a problematic behavior in WP 2.7.1:

If you edit a page in HTML mode and enter an entity such as ®, then publish the page, the entity correctly is displayed as “®”, not “®”.

But if you enter the entity in HTML mode, then switching to the Visual mode and back, the entity is translated to the actual character and left that way. So if you save a page that correctly uses entities, then come back later and edit, the entities will be stored as non-ASCII characters.

This of course causes problems with validation.