Zend certified PHP/Magento developer

How to make a graph in excel with 2 side by side x axis and one y axis

My question is how to figure a graph with 2 x-axis side by side with one y-axis. For clarification, i mean 2 x axis with minimum value (zero) at the middle and for example maximum value 15 at right for the first x axis and 20 at the left for the second x axis. While for y-axis, it will be in the middle intersecting with zero value.

Thanks