I have heard this in context of a kidnapping and asking a question only you will know the answer too.
The best solution to tell an imposter is by talking about a shared memory but changing some obvious details. You proof you are you by knowing the specific memory, they proof who they are by calling out the wrong detail.
Of course in context of a full clone, they would also have your memory and no amount of planning will help.
I have heard this in context of a kidnapping and asking a question only you will know the answer too.
The best solution to tell an imposter is by talking about a shared memory but changing some obvious details. You proof you are you by knowing the specific memory, they proof who they are by calling out the wrong detail.
Of course in context of a full clone, they would also have your memory and no amount of planning will help.
I always worried about something like that because I have a terrible memory