It seems there is an error with map duplication - Specifically with duplicating maps with default dialogs.
In project ST-HABHPTFCU I have a map where three contacts have a default dialog. I wanted to use the same map later in a mission so I duplicated it. The only issue is that it seems that every object was suddenly given not only one default dialog but three and I could not disable them.
As a work around I had to remove the default dialogs, duplicate the map and then reconstruct the default dialogs from notes I had previously taken.