Cloning error: Titles with same name result in "EventStream Connection Error"

[alex-418]

Prerequisites

• Can you reproduce the behavior you wish to address with all other plugins deactivated?
• Are you running the latest version of Pressbooks and the latest version of WordPress?
• Are you experiencing this issue with one of our built-in root or book themes?
• Did you perform a cursory search to see if your bug or enhancement is already listed?

Description

Cloning this book via the cloner at /wp-admin/admin.php?page=pb_cloner will result in EventStream Connection Error every time if the book contains content titles that are duplicated.

Steps to Reproduce

1. From the dashboard navigate to My Books -> Clone a book
2. Enter this book as the "Source Book URL" https://pressbooks.bccampus.ca/pathology
3. It will fail with EventStream Connection Error every time.

Expected behavior:
The book to be successfully cloned.

Actual behavior:
EventStream Connection Error and letting it run for a while (as per the documentation) does not work. Tried increasing server resources as well. The new book URL is not ever created, so it doesn't get that far in the process. It fails almost immediately.

Note: I can import using an exported XML file, but only if I don't select everything and bring in only uniquely titled content.

Here's the books structure:

System Information

Version: 6.8.0
Memory Limit: 512M