How do you deal with a person with multiple identity?

How do you deal with a person with multiple identity? They say, a liar is always a liar. Do you agree?

It depends on the circumstances.
I was a member here years ago, I left, and when I came back I had a new internet provider so rejoined as a new member

Where did you meet that person? A liar is always a liar, no excuse. The best thing to deal with that person is to not talk to him at all. Just ignore. If you can’t, just ride with him in a conversation.