A double; or loosely a twin; the "spit and image" ( sometimes called the "spitting image" ) and in a spooky sense a doppelg
When someone else writes about someone who is deceased, it is called a biography.
imposter
Karma.
When that someone said they did not like someone else you should have asked why they didn't like that person. It is called 'communicating.' If you like the person the other person does not like don't be afraid to say so.
Something that one person considers worthless may be considered valuable by someone else
It is called quoting (or to quote) the person and you should do also giving acknowledgement to the person and in which work he wrote it.
A group of people who have elected someone else to represent them is called an incumbency. This person will serve as an official post.
A twin
A Doppelganger is a person who looks exactly like someone else.
i believe that is called a low self esteem
An "impostor" is someone who pretends to be someone else, or who pretends to have status or credentials that he lacks.
Nothing. They could have had something in their eye. Why do little kids always make such a big deal out of people "looking at them" ??