supersession vs supersedure

supersession and supersedure both are nouns.

Word	Noun	Adjective	Verb	Adverb
supersession	Yes	No	No	No
supersedure	Yes	No	No	No

As nouns, supersession and supersedure are synonyms defined as:

supersession and supersedure: act of replacing one person or thing by another especially one held to be superior

supersession (noun)	supersedure (noun)
act of replacing one person or thing by another especially one held to be superior	act of replacing one person or thing by another especially one held to be superior