No Ash It's just that original St Lewis Hawken rifles had 2 wedge keys most of the time, so I put them into my recreations.
If we look at the British large bore rifles of the same period, most had only one, so we can safely say 2 are not necessary, but they don't harm anything wither.

Jake and Sam Hawken used 2, so I do when I make a rifle like the ones they did.