Media items blob deduplication

In previous versions, several media items might have referenced the same blob and this caused issues when such items were deleted from the recycle bin. From now on, the system ensures that each media item has its own blob. As a consequence, when a user copies a media item, or when a clone of a media item is uncloned, a copy of the corresponding blob is created.

To adjust previously created data to this behavior, after the upgrade, you must run a special page one time:

1. As a Sitecore admin, open the /sitecore/admin/Duplicates.aspx page.
2. Click Fix duplicates, then wait for the page to finish.