Safe procedure (especially for third-country documents):
• Have every page certified OR have the pages securely bound and the stamp placed in such a way that it "links" multiple pages.
• Ensure that the certification states "Copy matches the original" + date + name/office.
• Make 2-3 certified sets (you will often need copies again later for visa/job/Berufserlaubnis).
And: never send originals unless the authority explicitly requests it (very rare).