Right, I did that, but I still can't edit my duplicates. The colour selector for Background Colour, for example, will allow me to reconfigure the colours, and the changes will be reflected in the selector, but the changes don't take on the actual theme.
Here's a screenshot to better explain what I mean:
http://monosnap.com/image/waZmq0eBRVDTJLiLwSXhaAyyOGRg4G