Dark Magical Circle vs Masked HERO Blast
Since "Dark Magical Circle" stated:


  You can only use each effect of "Dark Magical Circle" once per turn.


No, he cannot use "Dark Magical Circle" to look at the top deck again at the same turn.

However, they are allowed to activate it again as a Continuous Spell, and use the effect to banish your card if "Dark Magician" is Summoned.