If you want independent chartIDs then you have to use File - New - Blank chart or Blank pane
Apparently you are using "Default chart" multiple times. Or you have applied a saved chart template multiple times.
You can check chartID via CTRL+R and then if being in parameters window go to Axes&Grids tab and at the bottom you can see the chart id of a pane.
Alternatively you can check chartID using following code
printf( "Chart ID: %g", GetChartID() );
then open Window - Interpretation to see output.