Multisite: Multiple copies of the same image in Media Library from syndicated posts

[peteschiebel]

Issue
When we syndicate posts between subsites in a multisite environment, we sometimes end up with multiple versions of the same image in the Media Library.

Details

• We recently switched from having multiple single-sites hosted on WordPress.com to having one multisite environment where all sites are now subsites.
• The issue didn't start immediately, but we didn't have it before then
• The issue isn't consistent, it doesn't happen every time
• Even when it does happen, it doesn't happen on every subsite the post is syndicated to. Ex: A post is syndicated to 4 other sites. 2 may experience the issue, with differing numbers of duplicates, and the other 2 may not experience the issue
• Here's a screenshot of the issue: