Sometimes users want to quote and/or reuse a text with LaTeX content. To do this, they copy text that contains LaTeX and has been processed by MathJax filters. Paste this text into another location and write further LaTeX code there. Now it is possible that the result is completely broken because the copied text still contains HTML markup with MathJax and this confuses MathJax.

Steps to reproduce:

1. In a course create a text and media area
2. Insert LaTeX code, save and return to course
3. Create another text and media area
4. Copy and paste the content of the first text and media area from step 1 in this new text and media area
5. Write further LaTeX code, save and return to course

Now the page can be completely broken.