The writer suggests in passing that the heavenly things, like the copies,
needed to be purified. He is now increasingly stressing the uniqueness of
Christ’s sacrifice, and therefore the contrast (better) between the old order and the new. The plural sacrifices means “a better kind of
sacrifice.” The verses which follow will emphasize that under the new covenant,
there is in fact only one sacrifice. (Paul Ellingworth and Eugene
Albert Nida, The Handbook on the Letter to the Hebrews [UBS Handbook
Series; New York: United Bible Societies, 1994], 205)