[ContentReferenceList] Undo action for multiple added items is unstable in OPE mode

Description

Steps to reproduce:
1. Add a ContentReferenceList property (Property1) to a content type.
2. Open a content item of Property1 to edit it in OPE mode.
3. Drag and drop more than one content item into Property1 -> auto-save runs.
4. Click on Autosaved > Undo.

Expected: The items added in step 3 are removed from Property1.
Actual: The newly-added items are still in Property1.
Notes:

• The issue occurs just after the first Undo action, after changing the property value.
• No such problem if only one item is added to the property or in All Properties mode.