I have a Galaxy 8 - when I edit my Contacts - like adding a person's new address and deleting the old one - it keeps both of them. The same thing happens with phone numbers? What is going on?
Welcome to Android Central! Is it possible the phone is syncing duplicate contacts from more than one account? If so those duplicates might be merged as one -- but if you edit it, it might be thinking you're only editing one of those entries. Select one of those contacts and tap Menu -- is there an option to Unjoin or Unmerge?