I have always been of the opinion that if a firearm has two barrels, it should have two triggers. Rifle or shotgun.
Single trigger doubles are a solution to a "problem" that I never knew existed.
They're "more modern", and "more uniform", newer, better, get one now!
Some single trigger designs were found to have ..issues..
like the ones that use recoil to reset the trigger for the second shot. If the first shot is a very light load, or doesn't fire at all, then you don't HAVE a second shot.
The best single trigger guns have a selector allowing the shooter to choose which barrel fires first. Many do not have this feature.
Do note the large number of heavy double rifles with single triggers intended for dangerous African game.....go ahead, take a look..I'll wait....
....
find many?
WHY do you think that is??
it's because for those guns, a RELIABLE second shot is extremely important.
Not stopping a water buffalo is a much different matter than not stopping a goose, I admit, but the principle still holds. A second trigger, (and lock mechanism) is more reliable for two barrels than a single trigger system.
Todays single trigger guns are quite reliable, but this wasn't always so.