Hi Erik. I do not wish to enter into a dispute as I accept that both the answers are correct. FWIW,
www.dictionary states that redundance and redundancy are synonyms in two separate places:
"Re*dun"dance (r?*d?n"dans), RedundancyRe*dun"dan*cy (-dan*s?), n. [L. redundantia: cf. F. redondance.] 1. The quality or state of being redundant; superfluity; superabundance; excess."
and
"n : the attribute of being superfluous and unneeded; "the use of industrial robots created redundancy among workers" [syn: redundancy]"