Search & Index tabs: double topic titles displayed

[Rob_the_Bonsai]

In my chm, on the Search and Index tabs, topic titles are displayed twice. The second instance of these does not display the topic when clicked; instead the "cannot display" error message is shown. If there are special characters (ü, ä, ö, etc) in the topic title these characters are displayed as a combination of weird symbols.
I cannot find anything wrong with my help project, as far as I can tell the topics that do not dispay do not exist in the help project.

[RoboColum_n_]

Are all topics suplicated in the search and index or just some and are these the ones with special characters. I am also a little confused by your last sentence. Do you mean that the topics that are duplicated are only in your help project once?

Can you also tell us whether the problem is only related to the CHM or does the same appear in a topic preview.

[Rob_the_Bonsai]

All topic titles in the search and index tabs are doubled; English does not have any special characters but the English projects are also affected.
The topics which are duplicated are only in my help projects once.
The problem only seems to be in the chm.

The help projects are in ClearCase source control - could this be a factor?
I have 2 separate branches of the same projects in ClearCase and one branch (the original branch) does not have this problem. The branch that does have the problem was created by copying the original branch.