Hey Jeff,
I’d say the second brisket of the same size would cook similarly to what you just experienced. You could add a bit more wood, depending on how much you used for the one flat.
But some pieces of meat are different and may take longer to or shorter too cook. I will add that if you purchased a larger brisket, packer style, say 12lbs, it would probably cook per pound quicker than what the 6.2# flat cooked (2 hours per). It’s weird that way, but that’s what I’ve experienced with my cooks.
Hopefully that helps. But enjoy that brisket! Nothing better than a cookout with friends and serving up a good brisket!