There are two ways at the moment which you can use to check who logged-in using social channels.
All users logged in by this plugin will have a role which you have set in plugin-settings. You can go in users-listing and check users against this role.
I understand there might be some users which have manually registered and given some role.
Other way around is we are adding some metadata in usermeta table for each user logged in using this plugin, you can queury you DB to check users against that, but there is no GUI to see this.
We can surely add some column to users-listing which can tell who all are the users which logged in using this plugin(login providers)