It is a bit tricky to see two series of values charted on separate axes within one chart, but the effect is well worth the effort. To see how this works, first create a basic pie chart. Put some data in the range B1:C5, and then select that range and click the Chart Wizard button in the toolbar. In Step 1 of the Wizard, under Chart Type, select the first pie chart. Now work your way through the Chart Wizard, making any changes you need. When you reach Step 4, make sure you place the chart as an object in the current worksheet.
Next, select the pie chart, right-click it, and select Format » Source Data » Series. Click Add to add another series. Select cell D1 for the Name and cells D2:D5 for the Values, then click OK. You'll get the chart shown in figure.
Figure. Pie chart set up from worksheet data
Double-click the pie itself again to select it, select Format Data Series, choose the Axis tab, and plot the series on the secondary axis. Click OK. The pie chart still looks the same on the surface, but it isn't the same underneath.
Select the pie, and while pressing the left mouse button, drag out from the center, then release the left mouse button. This will create the exploded effect you are looking for, as shown in figure.
Figure. Pie chart with exploded secondary axis
By exploding the pie, you will not only separate the two axes, revealing the second pie chart, but also compress the pie chart plotted on the secondary axis, allowing you to see both charts.
Now, select each slice of pie in turn and drag them back to the center of the pie, producing the chart shown in figure. Remember that two slow clicks will highlight an individual piece of the pie.
Figure. Completed pie chart containing two pies
Join all the pieces of the pie again, and you will have a fully functional pie chart plotting two series of data on separate axes. Now you can color and format accordingly.