dummy vs dummy up

dummy is a noun but dummy up is not a noun.

Word	Noun	Adjective	Verb	Adverb
dummy	Yes	Yes	Yes	No
dummy up	No	No	Yes	No

As verbs, dummy and dummy up are synonyms defined as:

dummy (noun)	dummy up (noun)
a figure representing the human form
a cartridge containing an explosive charge but no bullet
an ignorant or foolish person
a person who does not talk

dummy (adjective)	dummy up (adjective)
having the appearance of being real but lacking capacity to function

dummy (verb)	dummy up (verb)
make a dummy of	refuse to talk or stop talking; fall silent
	make a dummy of