dupe vs mug

dupe and mug both are nouns.

Word	Noun	Adjective	Verb	Adverb
dupe	Yes	No	Yes	No
mug	Yes	No	Yes	No

As nouns, mug is a hyponym of dupe; that is, mug is a word with a more specific, narrower meaning than dupe:

dupe (noun)	mug (noun)
a person who is tricked or swindled	with handle and usually cylindrical
	the human face (`kisser' and `smiler' and `mug' are informal terms for `face' and `phiz' is British)
	a person who is gullible and easy to take advantage of
	the quantity that can be held in a mug

dupe (verb)	mug (verb)
fool or hoax	To stare awkwardly
	rob at gunpoint or with the threat of violence