Suppose you have this son, let's call him "Mike." Imagine that one day, you get a call from the emergency room doctor saying that Mike had perished in a car accident. In response, you, in an emotionally unstable state of mind, frantically search through your son's daily backup files of his molecular state, find the most recent one, and produce an exact replica of your son Mike, with all the memories, etc.
Now, everything is all and good. Mike 2.0 has no recollection of such an accident because his memories were uploaded from the backup file prior to the accident, so it's as if he just woke up late in the day and continued life as normal.
However, a week later you get word from the doctor that Mike 1.0 has survived the car accident, and will be checked out of the ICU shortly. What do you do when Mike 1.0 comes back? Do you tell Mike 2.0 that he is a clone with the same memories and raise him like Mike 1.0's twin brother? Then again, remember that Mike 2.0 has the exact same memories as Mike 1.0 prior to the crash, so it would be unthinkable for him to imagine, with all those memories of years of his mother's love, to be relegated to the status of a twin or clone, much less imagine that he didn't even exist prior to the accident despite having memories of being alive many years prior to the week before.
You can't simply get rid of Mike 2.0 because he is, in the flesh, an equivalent human being with the same rights, etc. So what would you do?