change one entity's height reference, another entity will also be changed

I add two entities in the viewer.
When I change the height reference of one entity, another entity will be affected.
I just want to change the altitude type of one entity, not all entities.
In my example, I also find the outline's altitude of the green circle is incorrect.

Sandcastle example:

https://sandcastle.cesium.com/#c=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

Browser:
IE11, chrome,Edge

Operating System:
Windows 7, 10

Start by running the linked Sandcastle example in the Cesium viewer and inspect how the two entities use height references. Trace the entity height-reference handling and the green circle outline altitude behavior. Done means changing one entity's altitude type no longer changes the other, and the green circle outline uses the correct altitude.

Written by the indexing model from the issue text.