I actually looked at this as metaphorical, saying you can't not know what you know, you can't believe something you think is bullshit. But then that's my take as someone who doesn't come from an islamic background.
The thing is, the Quran always confuses the brain's functions with the heart's, so while yes, I agree that the point of the verse is mainly metaphorical, I do think that it is, in a sense, literal. Back in the day, a person with two hearts would be like a person with two brains. They would be technically two people in one body.
Moreover, some people think it's a Quranic miracle that people are never born with two hearts, so...