This is actually normal Joomla behavior. For pages that doesn't have assigned itemid (every page dynamically generated which doesn't have menu item defined) Joomla will show modules assigned to the default itemid (which is usually Home page of the site)
Search google how to overcome this behavior or try this
Create a hidden MENU.
Put a MENU ITEM in it for each (single) article you want on separate page (publish)
No need to put hidden menu anywhere - it will never be seen
Now joomla will open the articles in a separate page.
You can also take a look at Advanced Module Manager by nonumber.nl as a possible solution to this issue
However, with EasyBlog, all my posts are linked to one category.
In my case, all my categories are already linked to a menu item. So .. i would like to get this id instead of getting a default id.