That was it! The conflict is with the qtranslate plugin. http://www.qianqin.de/qtranslate/
I started a new thread in the qtranslate plugin forum to let the author know.
It would be great if someone here could confirm it. This worries me since it was the only multilingual plugin that I could find that would work with MU.
It puts language content in html language tags including titles. With that plugin off everything appears twice wherever I had added a translation.