This command lets you copy a vector mask from one layer to another as follows:
- In the Layers panel, select the layer containing the vector mask you want to copy.
- Open the "Masks" dialog.
- Apply the "Duplicate Vector Mask" command.
- In the dialog that appears, choose the target layer and click "OK".
If you want to copy the mask to all the layers check the "All Layers" checkbox (fig. 1).
In the screenshot 2, you can see the result of copying the vector mask from the "Shape 1" layer onto the layers "Layer 1" and "Layer 2".