Displaying different figures in 2 different columns in FSG reports

Hi

We have a FSG report which displays current month figures and the prior year figures for the corresponding month in the 2nd column

Due to a change in accounting code combinations in 2011 the prior year figures  show as nil as the current months code combination has values but the same was not valid earlier.

Is there a way this can be displayed in fsg with the same headings in the row

Or suggest some alternative way

Thanks

Ninad