When I set up two portlets on different pages and set one to open articles on the other page, the one configured to display the content shows all articles instead of the one that was opened.
STEPS TO REPRODUCE
1) On a site, create two pages called Page A and Page B.
2) Create two web content articles with some content in them.
3) On Page A, add an Asset Publisher Portlet with the following configurations:
Display Settings->Display Template->Title List
Under Look and Feel, change "Link Portlet URLs to Page" to Page B
4) On Page B, add an Asset Publisher Portlet with the following configurations:
Display Settings->Display Template->Full Content
-> Set as the Default Asset Publisher for This Page is checked
5) Click on an article in Page A's asset publisher
See the full content of only that article on Page B
See the full content of both articles displayed on Page B