Save Time by Cloning Sandboxes (Generally Available)
Where: This change applies to Lightning Experience and Salesforce Classic in Professional, Enterprise, Performance, and Unlimited editions.
How: Within each cloned sandbox, customize the data and metadata to accommodate the phase in your application life cycle, such as testing or staging.
From Setup, enter Sandboxes in the Quick Find box, then select Sandboxes. Next to the name of a completed sandbox, click Clone. Or select New Sandbox, and in the Create From dropdown menu, select the sandbox to clone.
When your new sandbox is ready, you can manage it from your production org like any other sandbox.
To clone a sandbox using the Tooling API, specify the ID in the SourceId field on your new SandboxInfo object.