This card also appears in the Commander Deck (Mirror Mastery):

http://deckbox.org/mtg/Fire%20//%20Ice

Reference: http://www.wizards.com/magic/magazine/article.aspx?x=mtg/daily/arcana/732

This is an instance of two card instances that need to be merged. The Commander version is at http://deckbox.org/mtg/Fire (along with another copy of the Apocalypse version) but without prices.

Thanks for reporting.

I have merged them, now only one version exists: Fire // Ice.