You can search for an existing rubric and use it as a template for any new ones.
NB: By default, only the grading forms that have been saved as shared templates are included in the search results. Since all Moodle teachers will be able to see shared templates, the ability to share templates across Moodle is currently restricted to the Moodle Administrators (please contact the team on firstname.lastname@example.org if you would like to discuss having a specific template added).
You can also include all your own grading forms in the search results (click the check box). This way, you can simply re-use your grading forms without sharing them.
Only forms marked as 'Ready for usage' can be re-used this way.
If you want to use an exact copy of the rubric, you need to nothing more. Should you wish to customise it in any way, simply click Edit the current form definition, make your changes and re-save.