Does that(yoke) stay in place when they change a meter? If it has a yoke, we don't need the jumper? I've always put the second clamp on any how. I guess it depends how close that the plastic is to the meter. No room for a second clamp? There has to be copper some where in the house, where it would need to be bonded back to the panel.
I would guess it does serve to relieve stress and keep everything in place if the meter is removed. This is the common configuration with inside Residential water meters on Long Island. Some older homes have buried meters near the street connection to the supply.
I sand the copper first, or emory it, then I put the clamp on. Then I put scotch coat on the clamp and pipe. (prevents corrosion on the clamp) There's a lot of humidity build up in these basements here on L.I.