Peer assessment qualities are lost when pages are added to a collection

Mahara 18.10RC2

When pages are created outside of a collection and the peer role is given, the peer qualities, i.e. not displaying content in blocks are lost when they are added to a collection. I believe it is due to the fact that the user who is a peer is listed multiple times and even if they show all the peer role, the content was displayed.

To replicate:

1. Create 2 pages: 1 with a peer assessment, the other without. Place a text block with some text on both pages.
2. Give another user peer permissions on both pages.
Correct result: On the page with the peer assessment, only the block heading is displayed. On the page without the peer assessment, only the notice "You cannot see the content on this page because it does not require a peer assessment." is displayed.

3. Add the pages to a new collection.
Expected result: The pages are displayed as above for the peer assessor.
Actual result: The content of the pages is displayed to the peer assessor.

On the "Edit access" page, the name of the peer assessor appears twice (or however many pages were added) and it seems that they are cancelling each other out.

Also, when you remove the collection and look at the pages separately again, the content is displayed for the peer assessor even after removing one of the access lines. You need to remove both of them, save the page, and then add the permissions back in to get it to work properly.