When a chapter is created , the name of the chapter by default appears BOLD-ed in the body part of edited chapter.
If you leave it unchanged , it may not cause problems. Chapters will have proper numbering, etc.
If you Change the Bolded part to something else - you will end up having two chapter names:
a. The one in the Table of Content: http://booktype-dev.sourcefabric.org/euro2012/_edit/#
b. and the one you just changed.
There should be centralized editing for the chapter names.
All the changes should be synchronised