engine vibration....damper?

Yes, that looks like a neutral balance damper. The one for your external balance 360 will have an obvious assymmetrical front flange.

Edit to add: However, now that I look at the 3 holes drilled in one side of the damper ring I am not so sure. The 3 holes seem to be a lot for balancing a simple neutral balance damper.
No, you're first statement was correct. The inertia ring will be asymmetrical. Damper in the photo is neutral balance.