If the bolts are tightened there shouldn't be any play. If there is still play it would be from the mismatch between the axle tube and eyelet of the shock.
The bolts should be tightened so that the axle bush gets clamped between the flanges of the shock mount on your bicycle frame. Then the axle bush and mounting flanges are "as one". The shock should be able to rotate over the axle bush and NOT the bolts!
Make sure the inside diameter of the axle bush is appr. the same as the holes in the mounting flanges.