That is a straight metal pelham; an English bit but not necessarily or specifically a walking horse bit. Yes, it is typically ridden with two sets of reins. The cheekpieces of your bridle attach to the top most ring, the same one with the hooks for the curb chain. Hooks go behind the cheekpieces. Can be used with a lip strap or leather or rubber in place of the curb chain. Snaffle rein goes on the largest ring, curb rein goes on the ring at the bottom of the shank.
Pretty difficult to set up correctly if you've never used one.
Also, a fairly harsh bit, especially with a curb chain, and not usually a Western bit.