Billy,
You might be able to cram 2 that big in a #1, but I never could. Too limited, vertically. It's not the weight, it's the volume. The bottom butt would be really close to the top of the smoke box, and would likely overcook on the bottom side. You would be better-off doing them separate, and saving for later. If I save a whole butt, I double-wrap in foil, let cool awhile, and then vacuum seal the package. You can reheat by removing the butt, still in the foil, from the vac bag, and let sit in a crock pot for 3-4 hours on low. When you unwrap and pull the pork, it's just like the day it was smoked!