Summer flicks don’t usually yield many Oscar-worthy performances — at least not until the Academy introduces a Best Explosion on the High Seas category. But there’s actually some genuine acting going on this season. For your consideration: John Glover, who does three wildly different turns in two wildly different movies. In Love! Valour! Compassion! the Tony-winning actor plays twins: one evil, one good…and dying of AIDS. ”An actor’s dream role,” says Glover, 52. In Batman & Robin he pops up briefly — but delightfully — as a mad scientist with a Susan Sontag-sticks-her-finger-in-a-light-socket hairdo. ”A cross between Albert Einstein and Charles Manson,” Glover describes him. Now, that’s range.