Why I want to do this: I've created a pivot table, grouping one of the date
fields by year, now I want to create another, but group the same date field
by quarter without affecting the existing one.

In Excel 2003 if you have already created a pivot table from a data range,
and then want to creat another from the same range, a pop-up with show up and
ask if you want to create the table from existing report to save memory. At
this point if you click No, Excel will create a seperate pivot table for you.

However in Excel 2007, it seems Excel creates the second pivot table based
on the existing one without asking. If I change the grouping in the new pivot
table, my existing table also gets change, and vice versa.

Any one has any idea how to alter this behavior in 2007? Thanks,