You can edit one of the blogs widgets, go to Advanced and find the UrlKeyPrefix property and set some value there (or for both widgets, but these values must be different). This will differentiate the two widgets.
In this case do the following:
In the first blog posts widget go to Advanced mode and set ContentViewDisplayMode to "Master". Then go to ControlDefinition -> Views -> MasterBlogPostsFrontend and set AllowUrlQueries to false.
Then go to the other blog posts widget and set its ContentViewDisplayMode to "Detail".
This should do it.
Well, in order for something to be displayed in the Detail blog posts widget you have to redirect to the appropriate URL of the latest post - e.g. blogs-page/test-blog/2011/10/19/todays-post. You can assign a code-behind class to this page and add logic to do a Response.Redirect to the URL of the latest blog post that you could retrieve with BlogsManager.
My suggestion is the following:
Set the two widgets ContentViewDisplayMode to Master and then add a third one with ContentViewDisplayMode set to Detail. This way both your lists will stay once an article is clicked and the third widgets will display the views of the selected item.
This is also how to use Sitefinity 6 to show a product menu and a product on the same page. In other words if you have two controls on the same page, one is a product list widget and the other is a single product detail view widget.
A typical menu and detail relationship.
Is there a comprehensive reference to the Advanced configuration options for widgets? I have seen references to Microsoft documentation for these, maybe they are a standard solution.
In any case thank you for answering this question.