I am not an expert in Va rifles, or any other school for that matter, but it seems to me that double set triggers would have been an option then as today. If a gentleman buyer had a few extra dollars, then he might opt for them over a single trigger. A frontiersman who wanted a working rifle with fewer things to break or go wrong in the field might opt for a single trigger of good design that would give him the same type of letoff that we look for in a modern hunting rifle today.
Common, yes. Universal? I doubt it.