Combined permissions will be a part of JFBConnect 3.0, which should be out soon. The reason that there are 2 permission groups is because the first is the 'required' group- if a user hits "Don't Allow" here, they won't be able to log in with Facebook. The 2nd set is "optional" and is shown only for permissions used to populate their profile (depending on what settings you've selected for mapping profile fields)- if they say no here, they can still log in, but their profile will not populate.
In the next version, we'll be adding an option to combine all the permission requests into one 'required' dialog. However, if you choose to map every profile field, this could present a very large permission request box which may deter users from allowing permission.
Hope this explanation helps!
Single permission request window
