multi-series grouped line chart differentiate the legend - kendo-ui

Question

Here is a DOJO for the issue http://dojo.telerik.com/aweDi/2
I have a chart that I want to display two different lines for each grouped item. The legend shows the same grouped item twice, once for each series, I need that grouped item named different for each series. any clues how to do that?
$("#rightLine").kendoChart({
dataSource: {
data: ko.toJS(my.rightLine()),
group: { field: "Grp_Value" },
sort: {
field: "MonthTrxDateFirst",
dir: "asc"
},
schema: {
model: {
fields: {
date: {
type: "date"
}
}
}
}
},
legend: {
position: "top"
},
series: [{
type: "line",
field: col
}
, {
type: "line",
field: col2
}
],
categoryAxis: {
field: "MonthTrxDateFirst",
labels: {
rotation: -90,
dateFormats:
{
minutes: "HH:mm",
hours: "HH:mm",
days: "dd/MM",
months: "MMM 'yy",
years: "yyyy"
}
}, type: "Date", baseUnit: "months",
crosshair: {
visible: true
}
},
valueAxis: {
labels: {
format: ty
}
},
tooltip: {
visible: true,
format: ty,
background: "white",
// template: "#= series.name #: #= value #"
template: tmplate
}
});