unreasonable vs undue

unreasonable and undue both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unreasonable	No	Yes	No	No
undue	No	Yes	No	No

As adjectives, unreasonable and undue are synonyms defined as:

Other synonyms of unreasonable include excessive, inordinate.

unreasonable (adjective)	undue (adjective)
not reasonable; not showing good judgment	not yet payable
beyond normal limits	not appropriate or proper (or even legal) in the circumstances
	beyond normal limits
	lacking justification or authorization