Unknown error when moving pages with child and parent both being duplicate

Summary

Moving Pages with duplicate parent and child names between spaces produces an unknown error:

Steps to Reproduce

1. Create a page and give it a unique name, i.e "test_page"
2. Create a child page under it with a unique name, i.e "child_page"
3. Go to different space and repeat steps 1 & 2 with exact same names respectfully
4. Attempt to move parent "test_page" page from one space to another

Expected Results

Error logged for parent and each child page in WebUI:

The following error(s) occurred:
The page 'test_page' already exists in space 'SPACE'. You need to rename the page title before moving it.
The page 'child_page' already exists in space 'SPACE'. You need to rename the page title before moving it.

Actual Results

The Following error appears in WebUI instead:

The following error(s) occurred:

• $error
• $error

Notes

The issue is not observed on Confluence 6.8.1
The issue is not observed when only 1 page is duplicate

Workaround

Attempting to copy pages instead of moving them will list correct duplicate page titles
OR
Get a HAR file while hitting the Move button and inspect the movepage.action request, the Response Content will contain the list of duplicate page titles