I don't think Moodle has built-in support for downloading multiple certificates.
However, it should be possible to write a custom plugin that allows multiple students to be selected and a combined PDF generated with all the certificates inside it.
You'd have to look through the code of the certificate activity to see how the PDFs are generated, then adjust that to add them all as pages to a single PDF.
However, it should be possible to write a custom plugin that allows multiple students to be selected and a combined PDF generated with all the certificates inside it.
You'd have to look through the code of the certificate activity to see how the PDFs are generated, then adjust that to add them all as pages to a single PDF.