RoboHelp 9 is creating two entries for every single topic in the Search tab. One link is correct, the other gives a "This page cannot display" warning. This behavior began recently after making a copy of the entire file to begin a new phase of the same project.
I've searched a great deal online for an answer (including P. Grainge) and have tried many approaches suggested. From generating a new .chm to a different folder, up to and including trying to edit the various system files, such as "projectname.hhp." (In this file I found topics duplicated, but editing out the duplicates made no difference.)