Okay so I've just purchased a used 2015 15" Macbook pro which potentially will replace my 2014 13" Macbook Pro. The former has 16GB ram compared to 8GB, same size SSD at 512GB, and dedicated graphics compared to just integrated. I know there is only a year difference between the two but with twice the ram and dedicated graphics the ability to upgrade to a 1TB SSD I'm hoping the 15" 2015 model will give me more longevity. I have cloned my entire SSD from one Mac to the other using my external backup drive and CCC. So now both Macs are exactly the same and running El Cap. I'm curious about Mojave and was wondering if it would screw up anything to install it on just one of these Macs to test it out? My backup is a bootable El Cap. Worse case scenario could I restore to El Cap from my backup? Also when someone buys a new Mac is there an easier way to transfer content from the old Mac to a new one? Can the two Macs be connected together via USB or something to migrate from one to the other?