properly vs duly

properly and duly both are adverbs.

Word	Noun	Adjective	Verb	Adverb
properly	No	No	No	Yes
duly	No	No	No	Yes

As adverbs, properly and duly are synonyms defined as:

properly and duly: in accordance with what is appropriate or suitable for the circumstances

Other synonyms of properly include appropriately, befittingly, fitly, fittingly, suitably.

properly (adverb)	duly (adverb)
in the right manner; correctly; suitably	in accordance with what is appropriate or suitable for the circumstances
in accordance with what is appropriate or suitable for the circumstances
indicating exactness or preciseness