There’s no specific option to merge reports. However, you can work around it as follows:
From the Reporting tab, click the first report and copy it as a workspace template.
Publish the template.
Edit the second report.
Add a new page wherever you want to insert the new content.
Select and drag the workspace template into the blank page.
This will automatically insert the content from the template and add the necessary pages.
Note: If you drag a template into a page with data in it, it will insert the new content into the next page.
You can then reorganise the layout.