Dear Maia,
The three references you refer to have their coding marked as "completed" and associated to Anne-Marie's account, you can see this information in the "Document details" window, through the "Coding Record" tab. Under these circumstances, even if the designated reviewer adds or changes the coding, the result will remain associated to Anne-Marie's account (once the coding is completed for a given item and code-set, the system starts to behave as if the code-set was in "single user" mode) and visible to all reviewers.

As you clearly wish two reviewers to independently assign the screening codes, the easiest way forward would be to remove all the screening codes from the three items concerned (get the list of the three "remaining" items, open the details of the first and remove all codes you'll see in the screening set). This will clear up the unexpected coding and allow your reviewers to proceed as planned.
Alternatively, you could:
Get the list of the three "remaining" items, open the details of the first, right click the green "V" icon on the screening code set and choose "properties". Untick the "Coding Completed" properties and click Save; proceed as above for the next two items. This will retain the codes applied by Anne-Marie, but will make them invisible to the other two reviewers.

I hope this helps,
Sergio