From what I have read and heard, they did NOT carry double bladed daggers. What they usually carried, as has been said on here already, were cheap users, like butcher knives. These were folks living off the land, many with very little money. They made due with what they had, and kitchen knives were always available. They'd put one in a sheath on them and go to work. They didn't use daggers for defense either, as that is what their guns were for. Not much a knife can do against an attacking animal, and when it came to fighting another person, they simply used what was on them. Again, this is what I have read and heard, so don't quote me on this, but a lot about the mountain man is produced by Hollywood.