Hi Erik,
I'm not sure that the easiest solution is to do it directly in Campaign. You may be able to do so with the different functions available from the expression editor, but I'd think, if this is a one time comparison, that it'd be easier to export the data you want to transform and perform the transformation/comparison from the file.
I'll double check with the team if there's an easy way I did not think of.
Florent.