can I copy keyframes of one mask to another but with different starting shape? I need to move it only in x-axis and y-axis, I mean no need to further change the shape. Just to like parent this mask of 1st one. If yes, please tell me how. Thankyou.
In the movie clip editor.
Select the vertices of the mask you want to move, then shift-select one of the control points of the other mask and press Ctrl+P to parent.
For example: this mask is parented to a tracking point.
If I create a second mask, and parent it to one of the points of the first mask, then they both move together.
If you don't want to create a new mask but duplicate an existing one. Just select the mask, and hit shift+D to duplicate it and move it where you want, all of the atributes and keyframes of the original mask will be duplicated.