My name is Ofer Barzvi and I'm a Team Leader in Check Point R&D.
I'm happy to share that recently we released a new version of Upgrade Tools for R81.10 and R81.20 with the ability to clone an existing Domain on the same Multi-Domain Security Management Server.
With these tools, you perform the cloning operation with the Management APIs export-management and import-management.
In the next R8x release, the cloning operation will be available in SmartConsole and with the new Management API call 'clone domain'.
For instructions, refer to sk180631 (the procedure will also be added to the relevant Administration Guides).
If you have questions about the Clone Domain operation, reply in this post.
Thank you