I have what seems to be an unusual situation. I had started two Plone sites on the same instance of Plone 5 (e.g., example.com:8080/Plone/first and example.com:8080/Plone/second ). The idea was that I would develop the two (with some similar, and some dissimilar content) with different themes. Such was the plan, and it largely worked for development purposes. I picked one over the other and set the site such that (e.g.) example.com/ --> example.com:8080/Plone/second .
The downside is that when I have a collection on the second site that is picking up objects from the first site. That wouldn't be a bad thing except for the fact that when there are two identical objects (one in first as well as second) then the collection lists both objects.
I revised the collection to look in only one location. Unfortunately, there is an identical location in the first site, so I still get duplicate entries.
Is there a way to force the collection to look only at one of the Plone sites? Frankly, I never thought that this would be a problem. I thought that the two sites would have had separate catalogs.