Postagem original de: Tom Chai ,
No there is nothing obvious from the outside. If you are sure that you did not lose or break any of the phones and buttons, it becomes a mathematical problem, how to test N devices and N+n home buttons the least times and find out the matching buttons. If you have time just go through every one of them. Each test has to be done with a software recovery, losing all data not backed up, force upgrade to the latest iOS and requires customers to unlock their devices on icloud.com. After that you can try adding fingerprints and if it proceeds successfully, you've found the matching ones.