Open the canvas that you wish to duplicate, find the actions on the left hand menu and select Copy, as seen here:
Here you can rename the copied canvas and select which project you would like it to be copied to, as seen here:
Once moved, you can remove the original canvas so that it only appears in the new location.
Note: This functionality is only available to project owners on the original and destination project. If you are not the project owner for both projects and need to move a canvas between projects, you need to contact the project owner to copy the canvases on your behalf. You can discover who is the project owner by looking under the Team tab on the project dashboard and clicking the first avatar tile on the left. If the project owner is not the same between the original and destination projects, this functionality is not available.