Moving Faces

I am new to the 3D features of Autocad 2000. I have come across a specific issue that I would like help with.
I have created a .5" thick solid plate. In the plate I placed several counter-sunk through-holes. I did that by creating a solid representation of the holes and subtracting the shape from the solid plate. Later, I realized that I needed more holes of the same size on the plate. I used the SOLID EDITING>COPY FACES command to add holes to the plate. Everything appears fine in the 3D WIREFRAME view, but when I view the model in the FLAT SHADED view, the new holes are "filled". The faces of the holes are there, but I cannot "see through" the holes in the FLAT SHADED views.
Is there a way to use the COPY FACES command so that the material inside of the holes is removed during the copy procedure? If not, is there another command that will easily remove the solid material from inside of the holes since the faces of the holes are already there? I am trying to avoid having to go back and re-create the solid model for the holes and do another subtract when this happens in the future.
Thanks for any help that you can provide.

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Unfortunately I have not worked how to do this either. I learnt my lesson and try and plan ahead. The only way is to draw one more and copy it around before doing the subtract operation.

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Okay. I'll have to wait to delete those "hole" shapes until after I am completely done with the drawing. Thanks for the input.

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you should probably make a copy of geometry you may need in the future by doing a writeblock command.
Bob