InDesign CC, latest version

Strange bug (or at least unwanted behavior) I encountered today in Indesign:

For a new book project, I used an earlier book as a template (a lot of the settings and styles should be the same), replacing all the text and images. The index in the earlier book contained 'see'-references. For the new book I generated a new index ('replace old index' checked), and the 'see'-references (just these) from the old book also showed up!
I would expect checking the 'replace old index' box would prevent this.
Not a big deal (the faulty entries were easy to be found), and certainly not a reason to change the way I work, but maybe something could be done about it.
Also see discussion on the forum.