Hmm. I can't say I have seen or experienced that exact problem. In the mid 1990s the trigger design was corrected by Jerome (Liege gun school graduate and the wunder kid responsible for the Darne double single AND single trigger design, both used today) to eliminate the side to side movement of the triggers common in many guns. Although my R model has some play, it is not as severe as a few I've seen. Pulling the trigger on a Darne that has substantial side play in it's triggers might cause what you are describing.
The "sear" is very easily removed from the breech on an R model for cleaning or inspection. My second thought on the problem you describe is a bunch of dirt and old lube being somewhere it shouldn't be.
What can you tell me about the gun that suffered the condition you describe? VIntage, model, gauge, etc?
I'm curious.
Best,
Ted
