Hello,
The method cloneWordContent (http://www.phpdocx.com/api-documentation/docx-path/clone-elements-in-docx) can clone elements but not whole sections in a step. Using this method you can clone a whole section selecting and cloning each individual element.
The easiest approach is to use the mergeDocx method (http://www.phpdocx.com/documentation/cookbook/merge-docx-documents). Instead of cloning the section, we recommend you to create a DOCX with the content of the section and merge it as many times as needed.
You can see a similar approach on this cookbook page:
http://www.phpdocx.com/documentation/cookbook/merge-docx-documents
Regards.