Differencing HTC Vive Grip Buttons

I am developing an app for the HTC Vive with Unity. I am trying to code some behaviour when pressing the grip buttons.

My question is how do I difference between left and right button? I mean, in each HTC Controller are 2 grip buttons, one left and one right.

At the moment I access them with Controller.GetPress(SteamVR_Controller.ButtonMask.Grip) but this way I get true when I press ANY of the two grip buttons.

Is possible to difference them, so that when I press left button I get X action and when press the right one get Y action?

You could setup tags on each of the controllers and check the tag to determine which controller is being gripped.