Would 2 small V60 brews (1 cup each) be less bitter than 1x large (2 cup) brew? I regularly brew my V60 for myself and my girlfriend on the weekends. However today I was wondering if I were to brew 2 separate batches instead one 1 big batch, would I get a less bitter cup? I'm assuming yes, because of the contact time between the water and coffee.

I use the 60g coffee to 1000ml of water ratio. So when I make 2 cups, usually go with 40g of coffee to 666ml of water.

I was wondering would I get a less bitter cup by doing 2 separate brews?
You'll definitely get a less bitter and possibly sour (underextracted) brew when dividing up one 40g dose between two V60s if you don't adjust the grind.

As you point out, the lower contact time of the 20g of grinds will lead to less extraction, and thus less bitterness, and possibly under extraction. This is just a characteristic of pour-over brews (as opposed to immersion brews) - grind size (and uniformity) is directly related to contact time and thus extraction, so the two variables can't be independently manipulated.