Editing PDFs with Markup is duplicating changes on pages I’ve copied and pasted

I’ve been using my iPad, Apple Pencil, and the files app to edit PDFs for school assignments. When in the PDF, I copy and paste the first page of the assignment template to create the needed pages. I can edit the pages individually, but as soon as I press “done” the edits I’ve made in certain places (specifically the small page number text boxes) revert to being identical as the first page, nothing I do is making those changes stick to the PDF. How can I fix this?