This is something I posted a long long time ago at the Zoogdesign forums and then was merged into the AUGI forums, about a door schedule however. A few releases later a better way showed up unannounced in the schedule features though it isn't obvious.
This involves creating a calculated value that we tell Revit to be "equal" to the other parameter we want to duplicate. Here's the calculated value dialog.
This is the resulting schedule based on my conceptual design for my special client.
This schedule includes additional parameters for a room name abbreviation and a client provided program area. I compare the actual area against "theirs" and get the difference. I used a shared parameter for the abbreviation so I can tag the "little" rooms with that instead. I just put two views using either in the image.
This is what the calculated parameter looks like for the difference calculation.