2x on iPad is a sloppy, ugly, lazy and stupid hack. Apple should stop the iPad from doing that and no one should ever use them. I refer to those as "iPhone only".
In iOS 9 those apps wouldn't get automatically installed on an iPad unless specifically purchased on an iPad. This behaviour has now changed. In earlier versions of iOS they did, but this changed in either iOS 8 or 9 (I can't remember which).