More than that, no one would use this spell since just one of both effect should clean the field.
Trying to example If i have a card at 5 that gives 7 damage to creature, is ok, but i would never put in the deck a card that with 20 cost gives 28 damage to creature, since the final effect is the same, killing a creature in any case.
It would be better only put the storm and lower the cost