Changing features in configurations

Is there a way to change a feature in one configuration without changing it in the other? Example: the part is a block 3" wide, 6" long, 1/2" high with a round hole in the center. I then add a configuration and change the round hole to a square hole. But the round hole also changes to a squre hole in the original configuration. Using SW ver 9 sp0.

Thank you

Paul

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