Double up on vitamins / prenatal?

I have a large bottle still of one a day women's which only has about half of some of the supplements I should have while ttc. So I'm wondering if it would be safe to take TWO instead of the one I take at bedtime. I just want to do this until they're used up, then I'll buy a prenatal. For example, this only has 400mcg of folic acid and I should take at least 800. It's also low for recommended amount of calcium and iron.
Is there a risk of giving myself too much of the other vitamins (like vitamin c)? Or wouldn't my body just pass the excess I don't need?
I have about two months left of this bottle (big from Sams club).
Any helpful insights are appreciated. Thanks