Using "Replace with child" creates 100+ variables

Using replace with child appears to create multiple undesired variables

1. Open the editor
2. Create a new widget blueprint
3. Add a named slot widget to the canvas panel
4. Right click the canvas panel > Replace with child
5. Open the Graph tab

Result: 100+ named slot variables will be created
Expected: The canvas panel would be replaced by the named slot and no additional variables would be created.