I don't note a problem with the first shot and the finger is light on the front trigger with a firm hand grip.

It is the rapid acqusition of shooting position on the second trigger that can cause "slapping" or whatever you wish to call it and a premature shot.I think this is operator error due to the firm grip on the stock and the natural tendency of the hard grip to cause the trigger finger to close with force.

If the Double is shot without a rush--no problem.
But thats not a worst case scenario and Doubles are designed for that quick second shot--

I want to get to the rear trigger and get both barrels off with aimed shots at close range(22 yard shot,then 10 yard shot) in about 2 seconds(faster than a big bolt cycles for 2 shots and animal closing at 25 mph).

Question--
Is this realistic with a big Double?