As I tried to tell you earlier (although admittedly not very clearly), every pig is different in terms of age, meat & bone density, amount of fat & connective tissue, blood chemistry, muscle tone, tolerance for pain, mood, disposition, etc., etc., etc. They're generally close, but not identical. As a result, no one factor (in this case, weight of a cut of meat) will tell you which will cook faster, taste better, be more tender, etc., etc., etc. Minor differences in cooking environment can also make a difference (even though you put the bigger piece in the supposedly hotter area of the smoker).
Mankind (with the exception of Murphy) is not yet scientifically or evolutionarily advanced enough to predict any of this accurately (and Murphy can only predict what will go wrong) without a computer model that will probably not be completed until well after anyone on this forum is eating mush in a nursing home.
OBTW, the same may hold true even for different parts of the same pig, not to mention cows (especially brisket) and other critters so get used to it.
Well, rats! While I was pontificating, Ted & mike answered succinctly. Story of my life.