You can look at duplicating the fields so you have you have 2 different year filters, one for each of the pie charts. You could also duplicate the entire data source and create pie 1 from data source 1 and pie 2 from data source 2. You can also ensure each filter only affects the 1 worksheet. There are options, have a play around and see what works best for your specific circumstances.
Thanks Andrew, how do I go about duplicating the filters. The option of duplicating the entire data source will no be possible as it is a live data and will be changing all the time. How do I ensure each filter only affects each worksheet. by renaming duplicating the filters or renaming them. Thanks for your help.
Sorry for the late reply. You should be able to connect twice to the same live data source - it's live so the data will be the same in both connections. This is effectively duplicating the source.
To duplicate a filter you actually duplicate the field. You could do this in the data source when connecting live - just bring in the same field twice but with different names.
By default your filters only affect 1 worksheet (I think). However you can click the little drop down on each filter to check it only applies to that worksheet.