Pivot Chart,dividing a column with 4values stacked into 2 columns with 2values stack

Hello,

i have an other problem about pivots chart i can't resolve by myself and would like your views about it...

In the attached file, I have a simple data table (which does not represent the reality) and a pivot table with 4 columns representing different values.

I created a pivot stacked column chart from the table, but I would like to rearrange the display of values.
Currently I have for each month a stack of the 4 values, however there is only a link between the first two, and a link between the last two.
So what I would want is for each month, 2 column with a stack of the first two, and for the second column the stack of the last two.

Do you know if this would be possible ??

Thanks in advance,
Regards