Looks like the bracket has one tab that sticks up & attaches to one bumper bolt. Appears to be a spacer that sets it back a little from the bumper also. Looks like an O.E. grade bracket, not a thin aftermarket one.
The front plate on our '70 is offset to the passenger side. I'll see if I can take a look at what the bracket looks like. The car was sold new to someone in Ohio....not sure if they had 2 plates or not.