I've Googled and Googled, but the only thing I come up with is how to copy a mask and make it a shape, and vice versa. No, Google! I want my two masks to have the exact same path.
I've tried selecting all of the motion/path keyframes and pasting them to the other mask, but it turns out wonky and flips the motion horizontally AND screws up the timing! What in the holy heck am I doing wrong??