Well as far as your question on two triggers goes. It's a double set trigger. When you cock the hammer, you then pull the back trigger. This "sets" the front trigger and it's a "hair trigger. It's adjusted for a very light pull.
I have two Ohio Half Stocks that you have to set the trigger before you cock the hammer. There is no half-cock notch. At first I thought that something was wrong with the lock, but have learned since that this is not unusual with some original Ohio rifles.
One of my rifles is unmarked and the other was made by a 'smith named William Kail from Tuscarawas County, Ohio. The lock on each is a "store-bought" lock marked "Riddle" and as far as I can discover probably came from a supplier in Chicago. Kail was a farmer/gunsmith from the 1850's thru the 1880-90's. (Farmed in the Spring/Summer/Fall and made a few rifles in the Winter.) The Kail is .29 or .30 caliber which is unusually small for the period.