duel vs dueler

duel and dueler both are nouns.

Word	Noun	Adjective	Verb	Adverb
duel	Yes	No	Yes	No
dueler	Yes	No	No	No

duel (noun)	dueler (noun)
a prearranged fight with deadly weapons by two people (accompanied by seconds) in order to settle a quarrel over a point of honor	a person who fights duels
any struggle between two skillful opponents (individuals or groups)

duel (verb)	dueler (verb)
fight a duel, as over one's honor or a woman