How do I swap the content of two phones I have two Samsung Galaxy S3 phones running Android 4.3 (one for me and one for my wife)

I no longer use my phone regularly (I switched to another phone) but I still need it occasionally (for things that only run on Android)

My wife's phone has a broken screen (a big crack on the glass in the middle of the screen, the screen still shows the image and touch and everything else still works)

I want to swap everything between phones so that my wife has the intact phone (with everything she now has on the broken phone) and I use the broken phone.

So, what is the easiest way to swap the entire content of two phones?
As both phones are identical (make that sure first!), there's even a possibility to "cross-clone" them:


First you'll need a custom recovery such as clockworkmod or twrp. Other than "stock recoveries", custom recoveries support...
nandroid backup: Using your new custom recovery, you can create a Nandroid backup of each device – which basically is a collection of "drive images" from all the partitions the device has. They will be stored on your SDCard usually.
Now swap the SDCards, enter the custom recovery again, and restore the Nandroid backup. With this step, the "body switch" should be perfect :)