Freeze and duplicate column. Load only the second column

Hello everyone,

is there a way to show a delta between a column (t-1) and a column (t0)?

I want to show the invoicing between two weeks. But i only have the whole invoicing amount of a project from beginning.

So i came up with the idea to duplicate the column with invoicing amounts and freeze the first column. One week later I only want to refresh the duplicated column and calculate the delta. Is there any possibilty to do so?

Kind regards

Chris