I am not aware of a report which will produce a comparative sales report by customer. I would suggest running the report (twice changing the dates) and then export them to Excel so you can combine the two into a single report with the information you wish. If this is a report you are going to want regularly, daily, weekly or monthly, you may wish to consider a report writer like XLGL. If the data you wish to obtain is in the data set then XLGL can extract it into a single report. If your particular report is not already in XLGL then you could create it or get Logicim to create it for you. Their costs are reasonable and service is excellent.