Steps to Reproduce:

1. Create a group and user with the same name.
2. Create a page and restrict viewing to the user you just created.
3. Attempt to also restrict the page to the group you created.

Expected Results:
Both the user and the group should appear under 'Viewing restricted to:'

Actual Results:
Only the first entity will have the restriction applied.

Notes:
I was also unable to add the group (if I had already added the user) via the group selection popup, and vice versa.