3) why 2 of the same chokes in a dblgun? First, consider how many superb clays shooters don't feel disadvantaged at all with a single choke in an autoloader. Second, consider that, outside of skeet and trap where all the targets are taken within a fairly narrow range of distance, choke is always a compromise. Seldom do you have the ideal choke for both targets in sporting clays. Having 2 chokes with anything less than 10 difference between the two is just silly. With a difference of 10 or more points, you'll be agonizing over which one to use for which target and sure enough you'll be calling for the targets wondering if one is too open and the other too tight. Better to have 2 that are always enough, without ever thinking about it. Twiddling with choke tubes and barrel selectors is a distraction. Mental focus is a scarce commodity on the clays course; gadgets don't help.
QFT (quoted for truth)
People spend way too much time fiddling with their chokes instead of worrying about hitting the bird. I'm not missing because my choke is too open, I'm missing because I missed.