Double set, single throw
Double set, double throw

"Double" simply means there are 2 triggers.

1st - means 'triggers' must be set in order to fire the rifle

2/d - means the rifle can be fired merely by pulling the front trigger, or the 'triggers' may be "set" to fire the rifle by then pulling the front trigger.

I do not see where there is a problem with this function.
When a set trigger is 'pulled' the front trigger kick backwards away from your finger and the rear trigger kicks forward as the spring tension causes it - usually - NP, as it must do this when the tension/contact with the sear/tumbler is removed.

Some people I've noted on other forums do not 'like' the way a set (front) trigger functions as it jumps back from their trigger finger - I've never figured out why they don't like this, but that's their deal - it's the normal function of set triggers and I love set triggers- have since my BRNO Fox I had when I was 20yrs. old - double throw, of course.

Single throw double set triggers, common back in the 18th and 19th century are a pain in the ass, especially when they make you bring the cock (hammer) to full bent, first. If you want to "unbend" (uncock) the cock (hammer), you must practically catch it when can cause accidents if the cock slips - we hates single throw double set triggers.