Dual Vs. Duel

These two words bother some Harry Potter fans more than anyone.

Dual: The word dual, mostly used as an adjective, means it is related to two things or objects.

Example: Dual SIM phones have highest demand in Asian countries.

Duel: Duel means a fight or combat between two people or two parties, using deadly weapons. Duel refers to a fight that follows a standard set of moves like that of karate or kung fu. 

Example: The kung fu duel between Neil and John was amazing.