Steps to reproduce
In site 1, create a quiz and link it within a Lessons page
In site 2, create another quiz
In site 2, use import from site and import just lessons from site 1
Within Lessons in site 2, you will see the following:
This item was copied from another site. It won't work until you do "Edit" and "Change Quiz" to pick a quiz that is valid in this site.
Click edit next to the linked quiz and press 'Change Quiz'
Selecting a new quiz and pressing 'Use selected item' the first time will refresh the current page.
Pressing 'Use selected item' the second time will create a new link in the Lessons page but leave the original quiz link on the page.