My half brother looks a lot like me. What would happen if I went to visit him, and we swapped lives: He returns to Canada as me, and I stay in Slovakia as him? swapping ID and lives and everything.

This happens on TV and movies, but would it work? in real life?

Hard to say. Not enough information. Do you each have careers? Do you each have the knowledge to step into the other person's shoes and their job? Are you trying to keep it a secret from others? Do you share the same mannerisms, hobbies, habits, fashion sense, tone of voice, sense of humor?