Move Tags (Library Window)
Move Tags does precisely that, it allows you to move tags from one column to another.
This feature allows you to quickly organize your tags. You can select the patches containing the tags whose locations you would like to change. Run this function and use the displayed dialog to select the source and destination tag columns. Pressing OK will actually swap the tag locations so that no assignments are lost.
To move tags:
Swap Tags Dialog
This is the dialog that is displayed when Library/Tags/Move Tags is chosen. The dialog allows you to select a source and destination tag column. When OK is pressed the contents of the two columns is actually swapped so that no assignments are lost.