The theory is usually bottom barrel first because it is closer to--or has a more direct line for the recoil to go directly to your shoulder, then recoil causes less muzzle rise/deviation, thus you require less correction for the follow-up shot through the second barrel.
So put the wider spreading choke in the bottom barrel for the first shot, & the tighter spread choke in the top barrel for the follow-up...
Understand that as the shot travels further away from the muzzle, it spreads further...so by the time the second shot has reached the target (that will be furthr away than it was for the first missed shot), the shot pattern would have spread out further to give you the same chance as the wider shot pattern did for the first shot...
have i confused you further...?...
The man who knows everything, doesnt really know everything...he's just stopped learning...