Materials are added to a Model that has been modified by Cube Grid

This is not a regression. Tested in //UE5/Release-5.1 CL23901901

Changing materials before making a change to a model with cube grid causes that previous selected material to be added to the model even though it isn't used.

1. Create or open any project
2. Change to Modeling Mode(Shift+5)
3. Select Cube Grid under the PolyModel section
4. In the Modeling Panel set the Material to "BasicAsset01" from the Engine Content
5. Select some point on the grid in the View Port then choose the action Pull in the Modeling Panel
6. Select Accept in the View Port
7. With the mesh that was just created selected activate Cube Grid again
8. In the Modeling Panel set the Material to a "BasicAsset02" from the Engine Content
9. Change the Material back to "BasicAsset01"
10. Select a face of the Mesh then use the action Pull from the Modeling Panel
11. Select Accept from the View Port
12. Select the model then observe Materials in the Details Panel

Expected Results:
Only BasicAsset01 is present under Materials.

Actual Results:
BasicAsset01 and BasicAsset02 are present under Materials.