Definitely 2, it gives you more consistency always and having 2 also gives you more draw on the long run, it's not like the probabilities of drawing the second book of the first one are high or anything. Yes for sure there will be times where you just get rekt like that but that is definitely not likely to happen.
Not playing two is not paying enough care to the value of the card in ''Minion-Mage''.
The card is just good. Watching Brian Kibler on stream with a deck running these two spells + 28 minions was actually a good experience. Kibler managed to stay toe-to-toe with most decks (thanks to Mojomaster and some accurate reading on the state of the hand of the opponent).
If book of specters Mage can hold the meta, it's a good Tier 2 deck looking onward.