Pete,

Normally, on 1 of the mounts, there is a grub screw that can be wound out 2 locate into 1 of the holes, or a fixed pin.
Most people use a single mount on springers, as they are more secure if the gun has a kick, usually only tuned guns will take two piece mounts, and as a last resort DAMPA mounts are also used.
Can you tell us what mounts and scope you have.

Steve