I am running the latest foobox free version plugin in a self-hosted wordpress installation. I think there is a bug in the caption system.
With this code:
[caption id="picture-2" width="300" align="alignright"]<img alt="ALT TEXT" src="picture-2.png"/>CAPTION TEXT[/caption]
the caption shown will be:
Usually, that will result in a duplication because the alt-text is just the caption-text.